We've never had one step out close enough that we couldn't stop, but winter roads can be slick and even having a moose begin crossing the road 300 feet in front of you in the dark is really scary. Without 4-wheel-drive and snow tires, I wouldn't feel at all confident that I could stop! Not that the driver or the stopability of the vehicle necessarily has anything to do with whether or not you hit a moose, if the moose jumps out immediately in front of you, or even jumps onto your vehicle. (It happens. You'd think they couldn't be stupid enough to do that, but when I was a kid, I was in a Suburban when a moose literally jumped out of a willow-filled ditch, over a guard rail, onto the hood of the SUV. Miraculously, no one was injured. Needless to say, the vehicle was totaled.)
Well, that's helpful: the Alaska DMV driver's manual is available online. Apparently the law only requires us to turn off high beams (switch to regular headlights) when 500 feet from a vehicle coming toward us, or 300 feet from a vehicle going the same direction. Is it accepted as common courtesy to switch off the brights sooner, though? I know it annoys me when a driver coming toward me from the opposite direction keeps his high beams on as he approaches... When there's a half mile of straight flat road between me and the oncoming driver, I don't know how close I'd let our vehicles get before turning off my brights.