I've been using a 5050 for several years and love it. Even at 'only' 5MP I can print large photos with no problems. Bigger/more MP isn't always better.
Last October I had the chance to try a SP-350. I was looking for a smaller rig yet one with the features I liked from the 5050. I really like the size and IIRC there is a feature that let's you take a RAW and JPG shot at the same time, or at least it records it in both formats, but it has a very slow writing speed. The lens wasn't as bright and the internal flash wasn't as good as I was hoping, it was only good for close macros within 12-14" and usless for anything past 20-24". One reason I wanted a smaller rig was so I could get away from the bigger rig with strobe, etc. So the flash issue was a biggy for me. I used it exclusively for 3 days and although I got some great shots from it, I hated to lose the convenience of having both CF and XD cards in the 5050 that I could switch back and forth and the flash thing I mentioned earlier. I decided to go with a really small P&S, Oly Stylus 740, for those days when diving is my main goal yet I'll have a camera with me for those once in a lifetime shots that always come along when you don't have a camera! I can carry and use it with one hand. If I need more camera than that, I can always carry the 5050 with no strobe/tray.
So I guess it comes down to whether size is an issue or if you're after the best results. For me, the winner hands down is the 5050. The 1.4 lens makes those WB ambient shots really nice, but the onboard flash goes a long way for both macro and portrait shots. I use an INON D-180 and the infra-red connection on the INON's work very well.
HTH