I used to run maxamps exclusively (6000 2s and pair of 4000's), but had a real issue with longevity. For just over a year I watched as my 6000 slowly started bowing in the middle and the power just vanished. My 6.5 in my T4 started feeling like a 10.5. Dents, bends, and other deformations of the cells will cause a loss in power (but not necessarily capacity) and that is why I now run trakpower packs and have loved them for over a year with NO change in performance. I originally had 2 packs and picked up a third 6 months later and the new one felt exactly like my older packs.

That being said, I wouldn't mind picking up their latest hard case 4200's.