ESC possibly holding back performance?

[BrianG]

An ESC with a lower current rating generally has fewer FETs, and that usually means the total resistance is higher as well. For a given current, the will be more voltage drop on the lower-current ESC because of this slightly increased resistance. Since motor rpm is a function of voltage and kv, that slightly lower voltage could translate into a loss of speed.

You gotta also remember that manufacturers rate their products differently. Some will rate the ESC based on the datasheet of the FETs without taking temperature derating into consideration, or allowing more headroom for the high surge currents found in car applications (compared to airplanes). From what I've seen of Castle products, they tend to rate their ESCs more realistically given the temperature and extra current headroom. For instance, the MM is rated for ~100A. The Quark 125B is rated for 125A. But the 125B and the MM use the same FETs and the same number of them. This illustrates my point exactly. Not knocking Quark, I love them, but you see what I mean.

Personally, the only advantage Quark has over Castle products is the smoothness of operation and the ability to run anything. However, with the newer firmware revision 1.20, Castle's ESC operate MUCH smoother and much more like how a Quark does.