a few things to note -
a) any servo can be hooked up to run on 7.2v, but the true fet servos likely have an internal motor rated to handle that voltage.
b) since fet servos will draw from your battery, the supply voltage is therefore not regulated. this means that, like your motor, your servo will now get slower through the duration of the race. yes, it will still be faster than running standard 6.0v, but the point is that it adds, yet another, inconsistency to work around.
fyi - airtronics 94758 is a digital 6.0v servo that has a .07/.06 transit time spec! freaky!
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