The amp draw might be the deciding factor... I've tripped breakers with many of my OP tools and rotaries. most 15 amp circuits will trip with a continual draw of 13.7 amps. I usually look for 20 amp circuits. The choice of pads, chemical and amount of solution sprayed can affect amp draw as well as thr carpet nap, construction and fiber material. I hope to run the new machine at ICE. In line Amp meters are inexpensive and provide useful information about amp draw with the wide choices of pads and cleaning solutions available.
HP has nothing to do with speed, take three OP machines, one on 1/2 hp, one with 1 hp and one with 1.5 hp, they all do exactly the same at 1725 rpm. Could be cheaper chinese leeson motors are having a problem with larger orbit, but zero speed change by adding more hp.