I didn't even using vats at all and whatever 4 me this bonuses. BUT I have some ideas to replace bonuses for vats to bt. Like a accuracy = critical chance(double damage when use it). Heavy weapons spend more ap. And any else bonuses can be applied to it, like an reload time, move speed, for melee hits from the back deal bonus damage and any else what we can imagine! Just need a people's who'd like to realize that.