A 950HP is smaller than an 850 DP. The 1000HP is basically the same carb as a 850 DP. So I'd say that you wouldn't see much difference at all between those carbs unless one of them wasn't set up correctly.

The 950HP is probably the best carb to run on the street but it might slow you down just a tad at the drags. Typically the 950HP will run better than a 850 DP on the street unless you have more than 500 ci.