That Rimfire on the stock prop with the Electrifly 640 15C pack will start to cut out at full throttle after about 15 seconds full throttle. Granted, you don't do that often cause the Rimfire has tons of power, but in vertical near out of sight climbs I did notice that. If that pack's rated at 15C you'll be fine, if it's only 10C, you'll have problems. With a 850 10C pack the thing would cut out so bad it wouldn't even hover.