I recently got rid of my Santa Rosa 2.4MBP for a unibody MacBook. I really wanted something smaller and felt as if the "power" of the MBP was superfluous. In all honesty, I feel like my new MacBook (2,4GHz version) is a good bit quicker than my MBP in daily use. Also, I'm more pleased with the MB in LightRoom -I'm not sure if I had any issues with the 8600m card, but i was never impressed by its graphics performance.
Truth is (unfortunately) the screen on the MB is terrible. It is a bit brighter than the previous MB's screens, but the quality is quite poor. I do miss the screen of the MBP a bit, but that is my only complaint. As I never did much graphics work with large files/gaming, I'm completely all right with the 9400m and everything else (even USB!

- it's a travesty, eh?).
One more thing to mention- USB 2.0 was no slower when transferring data to the new MB than when transferring via FW800 to old machine. Don't ask me how. This is only something I've observed - but it makes me question the quality of the FW800/drive I've been using.
Any more specific questions, feel free to PM me.