I've been using 6 volt 720 mAh NiMh packs in all my profiles... I love 'em... Kevin's right about the cliff at the end of the discharge curve though... I ran a pack in my taco all day... musta had 7 or 8 flights out of it.... and then it just tanked... controls got mushy and didn't have enough to land very well....

Just make sure to check them after every flight and never go under what they are rated for... I have a triton to charge mine with also and I LOVE it!!