I had been using silverback for over one year and still very good wor...... Some really old (1 year plus) and some newer all very good. Only balloon one as my son left it inside the car with the ESC on................. The rest are still perfer. Run time very good. Zombie good too, have very high punch but run time is slightly less then sillverback. Think it is like if you prefer runtime or punch la. hehe