I think if you averaged all classifiers, very, very few shooters would average their current percentage. Those that would keep their percentage are probably the very top GMs that would stay at 100 percent, because they really are shooting 110-140 percent now, but only getting 100 percent in the current system. Below that small group of GMs, you will have to either rejigger hit factors in each class, or downgrade virtually all USPSA shooters from their current class. Refiguring hit factors would make sense, since many have hit factors so high, you need to hero or zero to shoot a decent percentage.
I am not tracking your comment about making the current system "more accurate," maybe you can elaborate?