If your into high performance power heads you need to check out the 42 volt annihilator Ice gator, 3 year warranty on drive and 1 year on battery. About the same price for the power heads but with reverse and quite stealth in 10 to 12" of ice it can not be beat. There is a few who own the ice gator power head, they maybe able to give you more input.
Cabelas in East grand forks carries the Tanaka power head