I had a xtreme and initially found it to be a good receiver (I posted to this effect at the time). I did start experiencing problems though and ended up taking it back and exchanged it for a Topfield 4000PVR. If you do go for the xtreme make sure its a newer model (manufactured after April/May 2003) as some extreme's power supplies cannot cope when you use the optical output.
I recommend the Topfield though, its far superior albeit more expensive.
I have a Xtreme at my apartment which works well with fun 6 in 1, also switches between 13e,19.2e,28.2e & 30w using diseq. The software is quite fast, a big improvement on the Nokia 9800 I had there previously. I do not use the optical o/p and so far have had no problems.