RE: Battery longevity
Depo
So far (about 75 ish cycles) my 10s4p's are in perfect balance. They typically stay about 0.002-0.007V maximum difference in voltage between the cells. I do use balancers but not every charge and when I dont use them the balance is just as good as when I do use them.
Certainly less cells in parallel is better, but so far the TP 5300's seem to be very good at keeping balanced. I would not let their large xP count stop you from using them!