about "Pause and rewind live TV".
What is live TV there, as it is already recorded ... ?
Only users which didn't got into VDR and epgsearch timers do call for this live buffer function. They hope for a kind of security, which this function doesn't really provide.
You want to have a feeling how it feels, if a live buffer is the underlying central function in a PVR solution, just go and test MythTV.
Cheers fnu