This has been asked many times before and You all have attempted to address this with the picture in picture availability you recently added. This really does not work well (sorry). Most people are looking for the ability to switch back to the guide and still have the current show be playing in the top right corner of the guide. Not to drop names but I also use Plex it has this exact feature. if you are using their tv guide and you flip from the show back to the guide the show continues to play in the top right corner. It does this if you are using the apple app, the fire tv app, or the web app. Your process is well, let us say it misses the mark. It's a start but for example, I use the harmony universal remote. If I use the PIP feature (sometimes it is by accident it pops up) I actually have to go and find my apple remote to actually use this feature or even get back to full screen. I think most people are just looking for the show to display in the top corner of the guide not needing the show to continue to play even when you leave the app and attempt to go to another app. All in all, I love the app I use it all the time.
The overall UX of the Picture-in-Picture feature on tvOS is dictated by Apple's API, and there isn't much Channels can do to change it. Personally speaking, I'm grateful Channels has incorporated it at all, given the challenges involved.
You can also count me as someone who appreciates that the PIP window continues to play even when I leave the Channels app. To me, that's one of PIP's best functions.
OK, there is a difference between PIP and the show being displayed in the guide (lets call it PIG ). PIP allows you to move it keep in on even while the app is closed. I get that. Most just want the show that they are currently watching (that is the TV show prior to pulling up the guide) to display in the guide. Fixed unmovable and it goes away when you pick your next channel. Just like every TV cable guide does, and the plex app does it also. They have no issue with the apple API displaying a PIG or Fire TV displaying a PIG. If they are able to incorporate this feature as many other streaming TV apps do. I am just a little perplexed why this feature couldn't be incorporated within the DVR app. Again not a PIP that floats all over the place. Just a simple PIG....
I agree with you that PiP is not very usable. I tried it a bit on the Apple TV and its just not anything that would ever meet the Wife Acceptance Factor at all, and I think that is a key requirement for this kind of thing. I use the quick guide and that works pretty well if I need to scroll around. The fact that it now follows whatever collection is current makes it so much better.
Forgetting about PiP as any part of this, it seems like they could much more easily just build on the current QuickGuide and just give you a 1/3-1/2 screen Guide view at the top of the screen right where the QuickGuide is now, and call it a day. From a development standpoint, I can't see how it would be a lot different between a shorten segment of rows from the Guide vs. a QuickGuide. They both show similar data, just in a different format. One scrolls up and down and the other scrolls right to left. I'd personally rather have this than any kind of PiP implementation.
I agree the wife test should be the gold standard.
Unfortunately that's not a suitable "standard" since the acceptance levels of everyone's "wives" are different 
But I do hear you about the usability of PIP, specifically whilst browsing in the guide. Also, exiting the guide and resuming the PIP video back to fullscreen isn't as intuitive as it could be. Hopefully the Channel devs find possibilities for room for improvement in this regard.
In the mean time, there are several "ok" work arounds for different situations.
- PiP
- QuickGuide
- Hitting record on two shows if you want to jump between them, and then toggling back and forth from the Recordings screen to watch two shows without losing anything. Not really surfing, but its a related to this.
There have been numerous discussions on the forums here about why PiP is a technical challenge, most specifically because Channels often displays Mpeg2 video directly, which the native Apple player (among other devices) doesn’t support. They figured out some wizardry to get it to work in the pip window. Perhaps in the future if they do a major redesign they’ll implement a true “in the guide”preview. Fortunately, the current solution gets most users 90% there, in my opinion. Way better than nothing. 
If you make PiP automatic and move PiP to top-right, then when you go to the guide, the show continues playing at the top-right.... then when you pick a new show (double-click) it goes back to full-screen.
Just trying this again the way you suggested. It’s pretty good but need to see if my wife will not get it in some weird state that she needs the Siri remote to get out of.
That’s how it works for me even if I leave PIP in the bottom-right, I don’t have to put it into the top-right for it to work that way.
I tried it for a few minutes and turned it back off again. Too inconsistent. It worked reasonably well when I had it just turned on for Live TV, but when I switched it to all ... not so much. I may try it again when its just me watching TV on Live only, but wouldn't consider it ready for the family. I'm quite positive my wife will be texting me asking how to get the tiny window to go back to full screen.
It doesn't move to top-right on its own. You need to move it there. The question asked how to get PiP in the top right of the guide.
The functionality you are requesting, a cable-box like guide with PiP works with Hide PiP Button set to "ON" and Automatic PiP set to "Live TV". And the PiP box moved top-right. This is what you get on a cable box. All other settings are additional features that are non-conventional.
I didn't request it. I'm just sharing my experience.
For those using this on an Apple TV, if you have it set to PiP - Guide only, what do you do when you wander out of the Guide and don't come back. There doesn't seem to be any way out of it. If you leave Live View and even if you leave Channels DVR, you are going to have a PiP window trailing behind you. It works great as long as you are hopping back and forth between the Guide and a live program but at some point you go out of that.
It works great for both On Now and Guide. For library and outside of Channels, you would need to expand the PiP window.
In that case, I usually expand the PiP with my ATV remote, which is my all-in-one for everything. I don't even know where my other remotes are. The ATV remote controls my TV, audio system, apple TV, and all content.
I can see how this could be an issue if you have some kind of combination of 3rd-party remotes that don't have buttons which can be fully replicated.
I would guess that the majority of people do not use the Siri remote as their primary remote for everything, and it would never pass muster for the family as a primary remote. I also found things got a little wonky when I turned PiP for everything instead of just LiveTV but sounds like your experience was better.
The one thing that would make this way better would be if there were a way to hijack things from Channels and have some key combination get you out of PiP, but I'm guessing that is not possible since Apple has decided its controlled by the single most annoying key on the Siri remote..... the only one that can't work via IR. Who does that? Every button works with IR except one which only works Bluetooth. Again... who does that? What brilliant engineer at Apple came up with that idea.
Setting the PIP window to the auto setting and moving to the top right of the guide is a nice fix (on Apple TV). The only thing that would be nice is when I actually exit the app that the PIP window closes. Maybe a setting choice. Like "Auto Close" so those that want the PIP to stay open until they decide to shut it down might work. That would also fix the Harmony Hub Remote issue of not being able to focus on the PIP window. I actually need to dig my apple remote out to close the PIP window. Also maybe allow the placement of the PIP window on the Amazon Fire TV.
On the contrary, I would bet that majority of users with an AppleTV have no idea that an alternate remote control is even an option.