Bill
Depending on the venue, I agree with your evaluation of the two bodies. Particularly with portraits, I really like the CCD rendering of the D200 more than the CMOS of the D300. But the D300 has much more flexibility in more variable situations and conditions. Here's a link to an excellent comparison of the two units and other Nikon bodies by Bill Claff regarding dynamic range. Select the one under "Investigations" entitled "Photographic Dynamic Range- Nikon Only...". (Expand the image to read the index. The D300 is dark blue/12 bit with circles/14bit, and the D200 is bright green.):
Nikon D200/D300
Notice how the D300 has at least 1 full stop better dynamic range than the D200 at equivelant ISOs. But with the D200 at ISO 100 and the D300 at ISO 200, they aren't far apart. Then it's just a matter of which rendering you like best. The critical factor here of course is when it's feasible to use ISO 100. Either you have to have an abundance of natural or artificial light, or you need a very controlled environment, to be able to use it. Once you go over 200 ISO with the D200, from my exprience, it's lost any advantage and the D300 is much better. And even at 200 ISO, if set up properly, the D300 is superb. Bill Claff's website link also has other excellent articles for more Nikon related information like the above.