Good question. I used a workflow and exported to both JPG and .TIFF. HUGE DIFFERENCE. You can see it in the overal picture quality, really shows up in lines. But, it alos depends on what you are going for. If you arent shooting art, or something that requires clean/soft presentation, you can get away with JPG even at 80% quality (20% compression).
As for the color...again, using TIFF just makes everything look better, especially in low light shots.
At this point, shooting RAW on 550D is easy. The key is obviuosly a really fast SDHC or SDXC card, and a post production setup that allows a streamlined workflow. The only real decision to make is the frame size (1280x544, 960x540, etc). One doesn't need continuous FPS to get good shots. 24fps at 10 seconds is 240 frames recorded. More than enough to do get good shots, and move from subject to subject, shot to shot, etc.
In terms of "post processing", speed can be obtained by switching to an SSD drive, getting more RAM, and having minimum 2 procs, preferably 4 proc setup.
Cheers.
Yoda