Normally, I'm a "single mode" guy, but have a guest in the house so put the 622 in Dual Mode to serve the guest room.
I rather Tuners were not assigned to TV1 or TV2 at all. Why not have a 3rd "Record Plus" setting that gives either TV a tuner if one is available (including OTA) ?
In my dream world, with a 612, 622, & 722 all connected to my home internet, why should anyone ever "want" for a tuner. Crap, I have 6 Sat + 3 OTA tuners. Sharing them would be a beautiful thing. Yes, I realize the whole house solution is coming, but it should be possible to do this now with the hardware already sitting in the house. Same with sharing PVR recordings (which Direct already does).
Edit:
Here's another annoyance. So, I never watch Live TV (but my guest on TV2 does). I've switched to Dual mode with "Record Plus" preference to TV1. But, all the existing Timers still want TV2. Only way to fix it is to delete and recreate the timers. There really should be an easier way (like don't preassign Tuners -> like single mode, let dual mode pick on the fly).