Did a few test runs with 4S1P A123 in the Rustler geared 58-15 and 58-25, with the Medusa 4800kV motor. Peak Amps between the two gear ratios was off by only a few digits.
I used a Dimension Engineering park bec instead of the built in BEC. I peaked at 1125W, 181.36A@5.58V Power Graph
Have you noticed any difference between the 2 frequencies?