MIMF

I understand that 220 will yield half the amperage in the wire, and that total wattage is the same. (Voltage drop is negligible at 10-20' from my sub-panel)
My 20amp circuits with #12 NM-B wire are sufficient to power a single 1HP motor. (I make sure dust collector and machine being used are on separate 20amp circuits)
I am very familiar with the wiring pros/cons.

I am only asking about motor/tool performance or life effects.
110v will be a bit more flexible since I have a small shop and everything is on wheels.
I will definitely go 220 dedicated runs when I aquire machines 2HP and up.

Will my 1hp motors: run cooler/last longer/start better on 220?

Not really any benefit at 1 hp. Full load current on a 1 hp motor is 16 amps at 120 volts, which is just within the acceptable continuous rating of a 20 amp breaker (NEC 80% rule). The only benefit would be starting, particularly if under load, the in-rush current headroom of a 240 volt 20 amp circuit would make that marginally better. Ditto wiring heating, which would be marginally better with 240 than 120, but as you know the current is well within the ampacity of 12Ga wire. 1.5 hp motors are 20 amps full load, which is within the momentary rating of a 20 amp breaker and 12 ga wire, and might cause nuisance trips on hot days with a poorly ventilated breaker box. Momentary and continuous are kind of mis-nomers - NEC says three hours is continuous. Where you get gains in efficiency in a motor is going to three phase - those motors run with greater efficiency (less current per HP), run smoother and cooler.

Brian

I think Brian has explained it very well. That said, after moving a 1.5HP tool from one place to another, for convenience I rewired the motor from 120V to 240V (both circuits were short runs of 12ga wire. The tool seemed to start with a stronger 'zing', but it really made no difference in the performance of the tool.