I've been using the embedded Plex app (server running on our WMC box) to watch downloaded videos and previously recorded WMC programs - and it works pretty well, comparable to running Plex on other platforms.
A negative about the TiVo Android app is that it will only store downloaded programs in the device's memory - there doesn't appear to be any way to download programs to an SD card (could be due to DRM concerns), so that effectively eliminates downloading TiVo programs to our mobile devices for use on trips.
Next step in the eval is to get program transfer from our Bolt+ to a PC - and either use Plex to manage downloading to mobile devices or possibly just copy the files (especially to our Windows tablet and laptops, for use with offline viewing during trips).
Agree with the disappointment around the program guide data. The Rovi data has the same problems we are seeing on WMC. But, so far, I haven't missed any recordings, and the guide data does seem to be more accurate over the next few days - which triggers the recordings, and less accurate a week or so out. So as long as they can get the guide reasonably correct when it's time to record, it should be OK. And, at least we have someone officially supporting the TiVo program guide service, unlike the uncertainty with Microsoft's program guide service.
An interesting benefit of having a 3TB drive on the Bolt+ - while the TiVo software will delete programs, until the disk space is needed, those files are still on the hard drive and can be recovered, so if anyone ever accidentally deletes a program, there is a pretty good chance the file will still be there.
Yesterday, I finished installing the Minis - we now have 3 connected and installed the TiVo app on our Android devices. Plus, I programmed two universal remotes to control the TiVo boxes over IR (Harmony 900 and Pronto TSU9600).
Next up is to move the Plex server off our WMC box and figure out how I can transfer TiVo recordings to our new Plex server.