A 7.2v LiPo will give you close to the same ROF as a 9.6v mini battery, maybe a little lower depending on your setup.
It's not dangerous to the gun, however, ask yourself WHY you want to run a LiPo battery.
Is it for volumetric concerns? Do you want more ROF? Do you want to push a bigger spring at the same ROF without changing gears?
If your just looking for more performance in ROF and battery efficiency, simply installing a regular MOSFET switch and rewiring the AEG with high quality wire will audibly increase your ROF and noticeably increase battery life.
There are dangers and things to know about running LiPo, information can be found in this thread....
http://www.airsoftcanada.com/showthread.php?t=99899