One caveat about the G&P motors is the the quality of the pinion gears vary VASTLY. I personally run 2 G&P M160 motors in 2 of my high speed (35+ ROF) setups and haven't had a single issue. However, I've looked over 3 M120 and they all had differently designed pinion gears. A friend of mine has run several G&P M120s in his DMR setup and they ALL stripped or chipped their pinion gears. He runs a much milder setup ROF wise than I do. I'm not sure if the blame can all be laid on the pinion gears but they are softer than they should be.
As for Guarder, their QC can be suspect. I've had guarder motors come with cracked pinion gears right out of the box. The high speed revolution is garbage as well and will not last long when coupled with a strong 11.1v battery.
If you're on a tight budget, JG, SHS, and Element make surprisingly good motors with strong magnets and pinion gears.
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