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Ive used the 15amp cpu ones for years and they have been fine, they drove Alpha for about 2 years now theyre in Omega, both use(d) golds but with alot of load on them. Just the relays would give up after a long period of time. But i suppose golds are smoother and cleaner running then drills so would probably be worth adding diodes across brushes (which you should have anyway).

With drill motors I would prefer the 30A versions. Maybe even the 40A upgrades. You might get by on the 15 Amps, but why risk it?

remember that it also depends on your drive train setup as to what will be suitable, gear ratios, friction etc.

I would follow Leos advice to be on the safe side. It will save you in the long run