I bought four of the "supreme power" 100C 4S 6700 hard case Lipos in December of 2013. All of them were run in my MBX7 ECO, charged at no higher than 1C, always storage charged, and if I wasn't using them for more than a few weeks, I'd cycle them on my charger to keep them active. All four of them had a cell go bad within less than a year......

I switched to SMC 6500 4S Race Formula hard case packs , kept the same process, and have gone from that Mugen, to a Losi, and will now be running them in my new Tekno EB48.3. At less than half the price of ProTek, better performance, and longer life, it's a no brainer.