Just FYI, there is a new Sony HT-SS1100 (Approx £225) that is just being released next week... I've demo'd the Pioneer HTS, and it seemed OK, but not very hi-fi.. I think you are paying for the 360 'design'... but it looks a little odd perched on top of the 360..
It's 700W RMS, slimline amplifier, 5.1 setup as per the Pioneer, but it has
2 Optical / 1 Coaxial, 2 HDMI In, 5.1 analogue in / AV Lipsync
And a nifty Auto-setup via microphone setup..
I've heard the previous model, the HT-SS1000, and for the money that was certainly more impressive then the Pioneer and the 360 can sit on top of it quite nicely..
Just a thought..