I bought the Ride Anthem Boa boots earlier this season. I had them heat molded before I left the store. The fit pretty good and they are comfortable. My feet stay warm and dry which is good too. I will say that the boa system did loosen a lot at first but the more you wear them the less the loosen. On the first run they werena bout 3 turns too loose. By the end of the first day they only were about a quarter turn loose.
It's not that the boa is loosening, it's your foot settling/packing out the boot. I just walk around a bit and maybe give a lean or two forward and backward, then I can usually give a couple more turns and its usually good to go till I take them off. Occasionally I might crank them down once more at the top of the lift, but once I get them tightened down good, they stay that way. Same ones Donutz has, Ride Jackson Boa.