downgrading 5.1b2 -> 5.0.1

Hello MR users!

I've been running on 5.1b2 for a while, but i'm looking to downgrade because of specific spotify issues, which is really annoying me atm.

However the Back-up from the iphone (5.1) doesnt seem to be compatible with ios 5.0.1, as earlier betas were with original versions. Anyone know how to do this or will i basicly have to wait the time?

Thanks in Advantage

Belle