Benchmarks everywhere suggest that the 8600GTS performs on par with 7950GT, so of course it can smoke a X1950Pro. 8600GT competes with the X1950Pro as well as the 7900GS. All based on raw performance, that is. If they're priced the same, why not get one that supports DX10? Memory controller doesn't really matter, the card performs.
Plus 8600-series are finally seeing price drops. 8800GTS 320MB was the better buy because e-tailers didn't sell at MSRP ($299) but instead went for as low as $259. 8600GTS started at $199 and is already at $189
average and $174
being the lowest. The big thing is though, 8800GTS 320MB has gone back up in price, with $284
being the lowest, so buying a 8600-series is justified.
I don't see why some of you complains, you get what you paid for. If you can't afford that extra $100, then 8600GTS is the way to go.