I would love Plex integration. I think it would be a WIN-WIN for both services. Plex has multiple feature requests regarding using multiple guides (for users with multiple sources) and Channels already does that by default (OTA, cable, TVE) but Channels also has feature requests for "Watch Together" which Plex already has (so instead of pitting the options against each other, you could use both).
ChannelsDVR already includes an IPTV/m3u generator, it would be perfect to have a ChannelsDVR.HDHomeRun spoof where Plex could pull the guide and stream from Channels. That way, you can continue to schedule things in Plex, have virtually unlimited tuners due to TVE in Channels, you could turn on/off com skip in Plex, use the Plex settings to automatically delete shows once watched, etc.
I prefer Channels non-destructive commercial skip, but it's a separate player so when you import ChannelsDVR recordings into Plex, the commercials are still there (unless you create a batch file to ffmpeg the show to apply the cuts and then move the show to a folder that Plex imports).
That said,I prefer the layout of Plex, the web hooks that let me use trakt.tv (but I don't think there is anything wrong with Channels.) It's just I came across Plex first, bought the lifetime PlexPass and their current LiveTV&DVR feature is lacking in some ways that Channels already offers/supports. So I purchased Channels for the year and I'll keep paying for Channels because I see a value in their service.
I think adding a way for Plex to interface directly with ChannelsDVR (like xTeVe does with IPTV streams) is a way for Channels to increase their subscription numbers to those of us who already have lifetime PlexPasses and it's a way for users to get Plex functionality that their devs might not be able to provide immediately.