Roughly the same experience here in Southwest Vrginia... ASCAP went after several coffeehouse jams and smaller venues with local music. The local musicians lost piddly gigs, the businesses lost a minor draw - nobody won, everybody lost, but not much.
On the other hand, once upon a time, I had a piece of my music used in a made-for-tv documentary, (literally 28 seconds worth) and was quite thankful for BMI. Got a couple hundred bucks in the mailbox a couple times that year.
I tend to agree with stout71 above though - It's generally only worth it to register if there is potential for significant airplay or the chance of your music being played publicly a lot.