as far as i've experienced if you play well in an amateur division you'll place high. i had a buddy who never plays tourneys just kill it in the am 1 at the sf safari (one of the biggest norcal tourneys) scoring better than most of the pros in the first round. he slid back a bit, but he could've kept it up... why not?
i experieced something similar in the AM2. it wasn't an A-tier but seriously, minus the stupid mistakes and bad drives i'd have been playing "pro level" golf... i wouldn't be intimidated at all playing an A-tier. i think i know it's all up to me now. baggers beware

some kid throwing 100' shorter but not making any mistakes will win every time.
go for it dude. what've you got to lose? it's all a learning experience.