I have a 5D2 and a 1D3. IMHO the 5D2 is a mediocre body with rather weak AF that houses a rather nice sensor. In terms of performance as an all round camera the 1D3 completely owns the 5D2. It is a gorgeous camera to use. The 5D2, by comparison, is a right old clunker. The viewfinder blackout time seems huge and the mirror feels like it takes forever to do its thing. Of course, very fine images are possible, and you can push the thing to do things it wasn't really intended for, like sports, if you are lucky. It's strengths come in ultimate IQ, but it is quite lethargic, compared to a 1D3 or even a 7D, heck, even a 40D. Good IQ is all well and good, but if the AF can't keep up and the shutter lag or low frame rate misses the critical moment it isn't much use.
When the 5D2 was announced it didn't take long for me to put in an order. As I read reviews and user reports I changed my mind and ordered the 1D3 instead. I have no regrets about the choice I made. I only recently bought the 5D2 and the main reason as to improve my wide angle coverage. The 5D2 unquestionably has its strengths, but the 1D3 is a true pro camera and an accomplished all rounder.
Live music = 1D3. Extreme sports = 1D3. Portraits = 5D2, but the 1D3 is no slouch there either. It has beautiful IQ and will walk over any of the APS-C cameras for smooth IQ and better DOF control.
At the price now available the only downside to the 1D3 is that it is big and heavy. Sometimes that is a good thing. At other times it can be a pain. When I looked at the specs for the 1D4 (and the price!) I quickly lost interest. The 1D3 suits me well enough and will continue to for a long time to come.
Of course, if you want video (I don't) then the 5D2 pretty much has it, although you might look at the 7D, seriously. I have one of those too.