I dont have apple tv's on all my tvs and use plex on my other ones. Channels DVR is much better than the one i use for plex so would like to watch those recordings on plex in rest of house. Trouble is Plex sees the folder that programs are in and plays them fine but something is wrong with the naming of files because it doesn't get the metadata right so i have to guess what the recording is. I know this is a plex issue but was hoping someone here uses both and could help me. For some of the shows i end up recording on both so rest of family can watch them without having to figure out what the recording is.
Plex live TV and DVR sucks. The problem with recording it using both DVRs is that you're now using two tuners. Not sure if you have this problem, but I have personally seen Plex take a dump when tuners are concurrently being used by Channels. What devices are you using on your non-Apple TV TVs? Maybe you can install Channels there?
As stated above, be careful using Plex DVR with other DVRs. Plex doesn't play nice in those scenarios.
You have some limited options regarding Plex reading the files - You can manually update the recording from within the Plex interface and match the recording properly.
I am not sure what OS you have everything on, but if you're on Windows, you could use a program like MCEBuddy to rename the file in the Channels folder and move a copy of it over to a folder dedicated just to Plex. Then Plex will pick it up properly and you still have the copy on the Channels DVR to watch there as well.
These are not ideal solutions but it's somewhat workable. The naming Channels uses doesn't really work well with any other software (Plex, Emby, Kodi). Some shows are picked up fine but others are not. It's a little bit of a crap shoot.
Hope this helps some.
Channels dvr and Plex are both on a wd pr4100 nas. Use Roku on other TV’s so until channels makes an app for it have to use Plex. Also like that movies and tv are on same server. If channels made a way to connect my movie library to it life would be perfect. 
Easier for watching away from home. Plex always works out of house. Channels server sometimes is a crapshoot.