volts work harder
I'm currently running CC HV85 and love it. it was $20US for the USB link, and the latest software is a free download from their site. I have at least five soft to quick start settings and I don't even have the latest downloaded yet. I'm planning on replacing my other ESC's after this experiance.
Watts = Volts times Amps, so if you're flying a 8lb heli that takes 2000 watts for the flying you're doing, moving up in volts will draw less amps to hit that 2000 watts, so a lower Ah battery will last longer at high volts than it does at lower volts. Other factors apply, but that is the basic equation. I haven't run the setup, so I can't give actual data.
To get a set up that works, you need the pieces to work together to deliver an efficient combo of amps * volts. Some motors want to be geared low for high voltage, some want to be geared high for amps.8S 25C 3.7Ah run time
if we assume a usable Ah of 2.96 with 80% capacity, I think you're going to be around 5min drawing 40 amps average.
one really needs to set it up on the machine and fly, check the amps. Too many variables: Ambient temp, air density, blades, drive train, pilot skills, etc.