well its two issues we are discussing
1) at one point maxamps packs just werent up to an erevo class truck-
i would argue they are now.
2) cost is a huge issue - i wouldnt have bought these packs - they provided as replacements - somethng you wont get from a zippy or most vendors.
3) As a side i now have 2 SMC 9000 28C packs from SPC. I love these packs they are a great price performer.