I'm sure the 5700 can handle 4s for a while. In that respect I shouldn't be running my 6900 on 3s, but I do! If you're having problems keeping good gear mesh, try some lunsford fatboy motor screws with the cup washer design. It will help out alot for getting a good solid mount on your motor. I occasionally strip spurs, but thats after a serious jolt to the motor and me not rechecking the mesh. Also if you get an FLM transmission case it will hold better than the stock plastic case because the aluminum case won't develop little grooves from having your motor in different positions like the plastic one will. Otherwise, someone does make an aluminum spur, not sure who, I seen it on ebay, which in my opinion, if you have that much problem keeping good mesh, you'd probably end up blowin through that as well and cost 10 times as much. If you truly think you have too much power then yeah go mod1.