I have the DSP and and power amp. I haven't heard (or seen) the DVD so I couldn't really comment (although it does seem quite expensive for a player which doesn't appear to excel)
The DSP should primarily be regarded as a high quality stereo pre-amp which also happens to be an AV processor. I'm guessing that it's pitched at hi-fi people who also wish to do the surround sound thing but who are more prepared to compromise on the latter than the former. The power amp is IMHO a bargain. It's powerful and transparent. Both pieces are well-made and look gorgeous.
I'm shortly going to be upgrading (prolly to a Tag + Arcam P7). If you're interested in buying a second hand pair (in perfect nick) then let me know.