I'm in the same boat as you, I'm looking to spend up to about £400 on blu-ray/sacd player. I recently sold my Oppo BDP-83 and my Sony BDP-S360 (bedroom). I got £470 for the 2 and paid £100 for a Sony BDP-S370. I'm using the 370 as my main player for the moment and as has been said before, at 1080p playback the differences aren't massive. It's certainly better than the 360, less noise and a sharper image. How does it compare to the Oppo for picture, if you want your player to upscale SD to 1080p, it can't compete with the Oppo. In terms of HD playback, I'd say that the picture is brighter and slightly sharper, maybe a little less noise, but colours are a bit too vivid (although that has improved with burn in). Where I expect a more expensive player to show dividends is with sound, the 370 is articulate, but can sound a little harsh at times, not much low end grunt. It plays SACD's superbly for a £100 player, feeding a DSD signal via HDMI to my Z7, although lacking a bit in the midrange and low end.
I don't need internal decoding in a player and with Anchor Bay in my Z7, upscaling's not an issue either. I thought about the CA, but would expect it to perform pretty much the same as my outgoing Oppo. Blu-Ray is still improving, so the more recent Denon 1611 and the Sony BDP-S770 are the ones on my shortlist. For me, the Denon has the better build and chassis helping with a more stable platform for audio playback, plus DVD-Audio capability, although I expect that the Sony 770 will probably have a marginally better picture. I'm torn which way to go, whilst I respect Denon as a qulaity brand, their sound is usually too refined and warm for me.