I don't run the Zippy yet, but have a buddy running them in his Hot Bodies D8E, and loves them. He's running the 3S 5000 (not sure on the Mah) and a 4S 6000. As he said for the price you can't beat them.
Balancing is a good idea, however I don't on either one of my Orion 3200. As long as you store them with a charge they seem to balance themselves over time. they need balancing because the rate at which the voltage drops in each cell may be different. when you throw it on a charger one cell will get over charged and the other will be under charged, over time you will end up with a Lipo lat looks like and Accordion, all puffed out, or worse you could catch your car or truck on fire. I'm sure there is a better explanation but that's my understanding of the balancing.