a bottle heater doesnt work better then nano.
nano consistently keeps the bottle pressure at 1000psi until the bottle is completely empty. A bottle heater, as you spray, the pressure drops unless its a hot day out and then as you know when the bottle gets low, it takes even longer to bring the pressure up.
Nano vs a bottle heater is a no brainier. The ONLY downside of having nano is, when its very hot out, you got to put a chilling pack on the bottle to stabilize the pressure or else it will get too high.
people have picked up some solid gains going from a heater to nano.