An electronic regulator must produce slightly less field coil power than a mechanical (stock) regulator assuming both are in good condition. No switching transistor has zero voltage drop, a relay contact can come close enough to call it zero.
You can use Shottky diodes in a rectifier and gain a bit of power output, I don't know how much but not a great deal.
The difference in either of these is miniscule, really.
What happens when you draw more power than the alternator produces is a drop in system voltage until load = supply. Loads are basically resistors. Power load in a resistor drops exponentially as voltage drops. Alternator output drops linearly as field coil voltage drops. The voltage will drop to where these balance, below the battery full charge float voltage... the battery will contribute power slowing the voltage drop. Hopefully the balance voltage is high enough to keep the sparks sparking and engine running.
A friend tried a home made permanent magnet rotor using "super" magnets and a shunt regulator. It definitely made a lot of power... one stator coil burned out, a replacement lasted longer only because the magnets lost strength from being too hot themselves: those fancy magnets don't survive heat so well. Project is still in development.
There are alternator replacement kits claiming to give lots more output. Probably work but pretty expensive.
Passive thermal management is much less bother. Get a warmer jacket and gloves.
