As electric says, it depends on the gearing and stuff, but, geared to the same speed as the nitros I get about 12 minutes with 4350mAh 4S so 10 minutes with 4200 should be easily acheivable. Also, as you are already an electric driver, you should be a bit smoother anyway, so you should be able to get more run time than me
(faithful nitro driver originally; throttle on "waaah - waaah - waaah" through the corners
- not good for battery life)