Hello,
The Super Rooster will not be damaged by using less than 4 cells. But the ESC's Radio Priority circuitry is designed for 6 cells so you may not be able to get the full charge out of the pack before the RP kicks in. There is no damage, but it doesn't really work perfectly in that respect.
Almost forgot,
Anytime you need any assitane with Novak Products, you can always email us directly for information. We have some usefull technical data on our website as well, but we answer emails really quick most times.
Thanks for you time,
Chalie Suangka
Novak Electronics
949-833-8873
www.teamnovak.com