I can now comment on the whole PS3 vs 360 with regards to Burnout Paradise as I now have BP on both formats.
I spent all last night playing the 360 version, compared to playing PS3 since launch but I was on for a good 4 hours or so last night for the 360.
Connections wise, I'm using the official Component cable on the 360. Running at 720p on an LG32LX2R. On the PS3 I'm hooked up to the same telly @ 720p via HDMI.
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Colours: PS3 takes this one, but it could be down to the component cable. The picture is overall darker, even with TV settings tweaking. PS3 colours are brighter and vibrant. I will try hooking up the HDMI cable to my 360 tonight to see if it makes a difference.
Framerate: Again, PS3 takes this one. But it's a minor contest, very occasional framerate glitches on the 360 which don't occur on the PS3. Only happens at the start of races and when there's a lot of cars on the screen.
Textures: No noticeable difference in the 2 versions.
Models: No noticeable difference in the 2 versions.
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Moose Verdict: PS3 version is slightly superior graphically, but it's so minor it's hardly worth getting worked up about. Will double check tonight by hooking up the 360 via HDMI but doubt it'll make too much difference.