Too strong, would be equivalent to a 10.8v mini, or about 9.6v large battery
You can get a 7.4v 20C 1600mah LiPo from hobbyking for $9 each, they're brand name, and just a tad slower than a 9.6v mini.
Due to the increased amperage the LiPo provides, you could easily match the RoF of a 9.6v mini by using a higher speed ratio of gears.
And it will fit in a king arms AN/PEQ-15 with enough room to put a triggermaster SW-COMP in there as well.
Also, please read this informative thread on LiPo's if you haven't already
http://www.airsoftcanada.com/showthread.php?t=99899