Neu 1512/1.5D in Buggy?

[GO-RIDE.com]

Most everyone I've seen racing a 1/8 buggy conversion is using 4S. I've always read that higher voltage (lower kv motor) means cool electronics, less amps and longer run times per battery gram. I'm sure a higher kv Neu motor on 3S would be very fast too, but also draw more amps for a given speed and thus run both the motor and esc hotter. At least that's what I've been reading in this and other forums. Is there something I'm missing? I guess one advantage is the current ESC of choice (Mamba Max) can be run on 3S without an UBEC, but I assume it would run hotter due to the greater amp draw?

The other thing I've read is that two equal weight batterys (ie: same # of cells), but one is 3S and the other is 4S, the 4S will give a bit longer run times (even though the 3S has more Mah) because volts are more efficient than amps. Obviously, each has to have a motor that is optimized to its voltage for this to be a far test.

I'm getting ready to convert an 8ight so I've been reading up a lot on the choices out there.