I went to check out the XBMC PVR stuff in the new beta. I was always a big fan of XBMC right from the start out of XBMP so I'd love to use this. In short it looks like a nightmare. You have to install a backend and a frontend then manually load plugins and get the whole thing to talk to each other.
Contrast this with WMC where you simply click setup live TV then agree to a few terms and 10 minutes later everything is done for you.
It's a shame XBMC is so complicated I'd like to switch to a PVR that can record multiple shows from a single multiplex/transponder. It means that for freeview HD you only need 1 HD tuner and the rest can be cheap £5 jobs from ebay. With 6 tuners you'd be able to record everything that was on. I just don't want watching TV to be too much like real work.