I think you have a good idea going with the PVR option, I happen to be a fan of open source and with some tweaking MythTV (www.mythtv.org) might work.
With a few analog capture cards you could get control (and manually) set a delay and provide playback.
Its a DIY option but the people putting it together have lots of information on how to fine tune it.
If this is a route you would consider, let me know... I have plenty more ideas to get the most of the system.