I just ordered a Switchback from Mountain Models plus 2-8 cell 600 AE battery packs. I didn't buy the 8 cell Nimh pack because I would have to buy a charger too. My question is: How much difference is there between the 2 types of packs in endurance and power? Also if anyone has any building tips about the Switchback, I would appreciate them. Thanx RCNutt