I prefer the faster speed of the 9154 over the 9150, I've installed the 9154 gearset into the 9150 for conversion in some cases. Typically I replace the pots after 30 or so gallons of fuel (9411SA's seem to need pots & gears @ 20 gal.), I've not had gear wear sufficient to require replacement in 60+ gallons. A plus with these servos is the diameter of the output gear, roughly 2X that of a 9411, and high tooth count. The final gear is plastic which is driven by metal, all results in low gear wear. The 91xx is heavier than the 9411 and "feels" different, generally requiring much less expo. All these comparison are with a 5.7v regulated supply.