I think that the gap got closer when Lipo came around and variable timing speed controller, first brushless for TC came out around 2006/2007, Novak, LRP, Mamba etc were all there from the beginning, but we got the extra power in later years with higher C rated Lipo's.
IC are still faster in long straight line due to second gear giving them the edge (slighly) but with lower center of gravity and weight an EC is faster in the infield.
But all this in the right hands...
