I have a JG Dragon bought from Buyairsoft.ca last year, I have been running an Intellect mini 8.4V 1600mah battery in it...
It has niether BLOWN UP... or crapped out - the only problem I do encounter, however, is feeding from hi-cap magazines.
With this simple upgrade from 1100mah to 1600mah, your rate of fire increases between 3 - 5 rounds per second.
Capital Airsoft also sells Firefox mini 8.4V 1500mah.
If you're looking to just increase your rate of fire, use these batteries and you'll be very pleased.