I will say that the reason I have switched to RAW is because any post-processing will not affect the original RAW file. That to me, because I am still learning the post-processing part, is invaluable. If I start mucking about with my jpegs and keep losing quality, well, it's not worth it. And since I am pretty new to photography in general, a lot of my shots need edits. Ah, catch 22!!
With Aperture, you don't constantly lose image quality, all edits are done live. So multiple, successive edits do not degrade your IQ, the original is never touched!
(Unless, of course, you repeatedly export
as jpg and import again.)
Shooting RAW will complicate your workflow. If you still used iPhoto, I would strongly advise against it. Only with Aperture, Lightroom and the likes will you actually benefit from shooting RAW. RAW files take time to develop, they require quite some cpu muscle and eat up a lot more space.
Before shooting RAW, I would improve basic photography skills (how to expose properly, how to choose the proper settings for what you want). Then you know when you can actually improve IQ when shooting RAW (one example is shooting very high-ISO (ISO1000+ or so) and when not (a properly exposed photo shot at at ISO200, for instance).
So my advice is: learn the basics first, then you know what the benefits of shooting RAW are. In standard photographic situations, you will not be able to tell whether a properly exposed photo was shot in jpg or RAW.