Again, score one for the S2Pro actually. The noise on the Fuji looks better than all of them across the board. I would have liked to see what the grey card comparison looks like on the s2 pro.
I can't explain exactly why, but I subjectively prefer the D70 grey card from iso 200 on up to both the canon (10d/dreb) and D100. To me, the Canon at 100 and the Nikon at 200 look about the same on the card, although the std deviation and color channel says otherwise. It could be that at such low noise there really isn't much of a difference.
So, as I see it the S2 pro advantages over the D70 are:
Real TTL compatability
lower noise
lower moire
Better body build
better viewfinder
12 MP interpolated (is this an advantage?)
I'd have my housing already :-(
The D70 advantages are
lower price
better flash system iTTL/faster sync speed (once u/w strobes catch up)
faster continious speed with larger buffer
smaller RAW file size
liter body
better battery option (single rechargable battery)
kit lens price boost
They both accept the same excellent lens system wich is a strong advantage over the Canon.
With e-bay prices on the S2pro, and a sigma basic 17-35 mm lens, I figure the s2pro is about $6-700 more expensive, which basically means I can get a 60 mm macro lens, flat port, and a 1GB card, or a 10.5 mm fisheye lens for free.
I'll bet that all three are more capable cameras than I'll ever fully utilize.