I think you see some zippy bashing because people who sell the lipos that cost three times more are concerned they cant compete. I have run them now in the e-revo, emaxx 3905 and slash and see no real performance issues vs Neuenergy and maxamps in real world racing and bashing. The neuenergy's are the ones that get pretty warm where the zippys and newer maxamps dont. the neuenergys wires were cut from the case opening where they come through - ie no reinforcement, the cases open - have to seal them shut etc.
I am not that impressed. they may hold their voltage longer but in real world ie - not trying to break speed records in front of your house the zippys seem to be no better or worse than other batteries i am using and we push the models pretty hard.
the reality is that if you misuse lipos- dont use LVC's and or let them discharge they are going to fail. if you charge them at the right C and keep them balanced the zippys are just fine for most use cases