I'm about ready to take the plunge and get a new battery for my girlfriend's mini. it's a 1st gen one and i was checking out the 2nd gen batteries on ebay that are a bit bigger--650 mAh instead of 400 ish.

is there any reason NOT to get the non-apple batteries that have higher capacity? i've seen 750 and even 850 mAh.

are those alright? or should i stay away?

ps. I'm afraid of hurting the plastic end covers :(