Actually, unlike FD, Slashback can actually cancel an airdash. Not only will you turn around, you'll also drop faster and travel less far horizontally if you do it early enough, and it works for most characters with airdashes. I use it primarily to cross up, get ground confirms or high-low mixup from IAD overheads (by falling faster), or just to confuse my opponent's spacing. As an added bonus, it means you can slashback from an airdash faster than you can block, meaning that at least in theory, if you know something will hit you out of your airdash and you won't be able to block it, you should always try to slashback it.