Bryston 9B-ST or Pass Labs X5

I was wondering what sort of thoughts people had on using a Bryston 9B-ST or a Pass Labs X5 in a home theater set-up with the following equipment:

Processor -- Sunfire Theater Grand II
DVD -- Sony S7700 (soon to be upgraded)
Front Speakers -- Nautilus 805s w/ matching center
Rear Speakers -- Natulis SCM1 (flat, wall mounted version of the 805)
Interconnects -- Nordost Red Dawn (Balanced)
Speaker cable -- MIT T2 Bi-Wire (front)
Nordost Super Flatline Mk. 2 bi-wire (rear).

Any thoughts would be appreciated. Originally, I thought about using a seperate 2 channel for the front speakers and a three channel for the rest, but have ruled that out due to space (wife) considerations.
No experience with the Pass Labs, but I've been using a 9B-ST for the past 2 years and am very satisfied, both for HT and for 2-ch listening. It's a great amp.
I'm currently using Bryston amps with a theatre grand II for HT and it works very well. Have never heard the other amp, though. If you're going to use a 9b for all 5 channels, be sure 120w (8ohms) is enough for your fronts for 2 channel listening.
Concur with Dbwl above about power...although the Bryston is very conservatively rated. My 9B is spec'd by the factory at 170w/ch.

Your Nautilus are pretty efficient so don´t think you might be on the power challenged situation.
On the other hand been a HT setup and 805 not going that low, do you have a subwoofer in your system? Did you overlook telling about it ?
Thanks Sol322 and everyone else for responding. In fact, I have a REL Storm III as the sub in the set up. Based on the responses here and my own demo, I am leaning towards going with the 9B.