The guys worrying about 4 cell obviously have not run a 1/12th scale car recently. We run 19T/10.5 4 cell 1/12 here in FL. Our lap times are 1-2/10ths faster than open sedan mod at most outdoor tracks. It is not slow by any stretch of the imagination.
We run mod 1/12th once in a while. The last time we ran we were clocked at over 50mph on the back straight with 5.5BL on 4 cells.
We have tested the BMI DB10R on 4 cells with a 5.5 and it was just as fast.