As for which takes sharper clearer images... if it could be said that one clearly took sharper clearer images, then the other wouldn't really be shifting any units. I expect picture quality means a lot to everyone... It depends much more on the lens... and of course on the photographer.
The 30D is undoubtedly getting an "upgrade" or more to the point a replacement. So is the D200. So is every other camera. Honestly, anyone looking at any system has this dilemma. I believe it would be unwise to wait unless you know that the new model is coming very soon. Why? Because you can make photographs with the 30D, which you can't do with no camera while you wait. I think you're right not to be concerned by megapixels. I also think a different dust reduction system is probably not worth a wait and a higher price... there are several dust reduction systems used by various companies and none are totally effective... I can't see Canon suddenly discovering the holy grail there. Sensible lens-changing and occasional cleaning is not that hard.
The 30D is undoubtedly getting an "upgrade" or more to the point a replacement. So is the D200. So is every other camera. Honestly, anyone looking at any system has this dilemma. I believe it would be unwise to wait unless you know that the new model is coming very soon. Why? Because you can make photographs with the 30D, which you can't do with no camera while you wait. I think you're right not to be concerned by megapixels. I also think a different dust reduction system is probably not worth a wait and a higher price... there are several dust reduction systems used by various companies and none are totally effective... I can't see Canon suddenly discovering the holy grail there. Sensible lens-changing and occasional cleaning is not that hard.