Switch backs actually aren't that much more difficult than a regular back. The rotation isn't hard to get and you can spot your landing through the entire trick. If you have a solid backflip and can ride switch, they're an easy step. Working against the "grain" of the jump isn't a problem because of the way you pop. You just resist the jump's pop with you toes (kind of like a tantrum on a wakeboard, if you're into that) and look back and you pop right around. Switch fronts on the other hand are tough to control. They are more difficult to spot your landing on and the timing on the pop is more difficult. Off from small jumps they aren't too bad (though definitely harder than switch backs and regular fronts and backs) but if you go big, pretty difficult. That's why you don't see many pros doing them...