I love my D200, and am in no hurry to replace it. I tend to shoot at ISO 100 whenever possible. The D200's high ISO isn't as good as newer cameras, it's true. It is head and shoulders better than my old D1X, however.
The JPEG images out of the D200 are soft and a little dull looking. I shoot almost exclusively in RAW, though, so that's not an issue for me. If you shoot JPEG, you'll want to either turn up the in-camera sharpening a lot, or apply sharpening in post. If you sharpen in post, make sure you shoot at the highest image size and quality (large/fine). The JPEGs from the D200 hold up to adjustment and post processing quite well, considering.
If you buy a camera with stuck pixels, you should build the cost of Nikon service into the total cost of the camera. Supposedly pixel mapping is quite simple. From what I understand, all sensors have a few stuck pixels, and they are mapped out as part of configuring the camera.
I shoot a lot of macro, and there are tons of samples in my gallery (link in my signature.) All shots from the last several years are with my D200. The older images were shot with my D1X, and marked as such.
If you want fast focus, you should plan on using an AFS lens. Motor-driven lenses don't focus nearly as fast. I've always been happy with the focus speed on my D200, especially with my 70-200 VR. Then again, I don't shoot birds in flight very often.
Take a look at my marco lighting gallery. I've tried all different kinds of lighting for macro, and finally settled on a $10 pop-up diffuser attached to the front of my lens. It gives results that are far superior to anything else I've used, including a $400 Sigma dedicated macro lens. It took a little tweaking to get it to stay securely on the front of my Tamron 90, but it was worth it.