Forget the minewt, and get a magicshine. Or get two magicshines. Or one magicshine and two batteries.
All bikers owe magicshine props, because magicshine has exposed the bike light industry for the overpriced/overrated products they were producing. Several name brand now have decent models in the $200 range. Without magicshines influence, I doubt if we could get a decent branded light for less than $300.
I've had no problems with mine in about two years now. I've mtbd, adv raced, camped, and caved with the thing and it still works fine. Best bang for the buck out there.