I ended up buying the 55-200 about a week ago and ran a bunch more comparisons against the 50-230. This time I used Raw and shot with the same settings (manual) on a tripod (ois turned off). When shooting handheld in jpeg at the store, I couldn't see any difference in image quality even when pixel peeping. When shooting off a tripod in raw I did notice a small difference in IQ. You'll have to pixel peep at 100% to find it though. Here's a couple of comparison shots, 100% crops, shot off a tripod in raw and developed with exact same settings in silkypic:

shot from about 14 feet away @ 200mm f6.4

again 200mm f6.4 but this house is about 1.5km away
The other thing I have noticed now is that the 50-230 seems to be slightly faster at focusing. I don't notice it all the time but in certain situations its there. Don't know if its due to the decreased weight of the lens or what.