Personally, I would avoid them as much as possible.
They chew to no end, can escape alot easier than mice or rats, and if by chance, you happen to run out for a while, and your snake has become accustom to eating only ASF, you're screwed.
You can always find rats or mice, ASF's, unless you happen to know someone, or are willing to pay out the arse for them, you're screwed.
I breed them, have way to many of them, and out of everything I breed, which is alot, I hate them more than anything else. They waste more food than any other rodent, they eat themselves, they escape, i hate them.
did I mention i hate them?