[SpEEdyBL]

I think you should get the 4600 and run it on 3s. It should be slightly faster than the 7700 on 2s, despite the rpm difference. When you want to put big tires on your vehicle, just reduce the cell count to 2s or 6 cells nimh so the motor doesn't demand too much power. You can do the same with the 5700 and it will be faster, but you might have to deal with overheating issues. Most people who haven't tried or seen 3s lipo (I'm not saying you haven't) underestimate it's power.