-First the NPVR app channel changes were very slow (fixed with help from here, I had too many decoder options selected)
-Second the XBMC addon took even longer to tune the initial channel
-Third the XBMC channel change would never work without using stopping the current channel first
I'm using XBMC Frodo RC3 with the latest addon from the dotnetdevelopers page and NPVR 2.5.9 w/ latest patches
All of this in conjunction with HDHomerun Prime and a Comcast cable subscription
-I noticed a small improvement in the amount of time it took to tune a channel in XBMC by disabling unnecessary decoders within NPVR settings
-I noticed another improvement in the time it took to tune a channel by selecting XBMC instead of NPVR as the application in the HDHomerun setup
I'm still not able to change a channel in XBMC without using stop first
Another thing I noticed is the keyboard shortcuts for PVR addons in Frodo aren't well defined
Just to clear things up neither +, -, up, left, down, nor right arrow keys will initiate a channel change with the default keyboard settings within XBMC
I can't find any documentation that confirms this, but pageup/pagedown will "attempt" to initiate a channel change. The OSD will popup with the guide info from the next or previous channel (depending on which way you went) but the channel will never change (as others have mentioned) it just buffers continuously until you exit or it reaches the timeout number you specify in the PVR addon settings menu