Maybe it's just a matter of preference...
We can obviously agree that the Higher voltage setup are more efficient.. but speed wise and heat issue... really depends on the setup, gearing, driving condition and habits...
Of course you'd have to use different gearings with different voltage setups...
Maybe it's like comparing Apples to Bananas..
Finn is right too... same of total battery power (88.8 Watts) so run time would almost be identical...