IMHO dont waste your money on mimhs,God knows how much a specialised orion twin pack is!!..check out hobbyking or even ebay for a Turnigy 3 or 4 cell lipo,I have been running a 20c 3 cell for the last 8 months and with regular balance charging it has been faultless.
EDIT- Obviously presuming your charger has a lipo charge setting
