frame relay vs managed IP VPN

We are currently using frame relay to connect 27 remote sites to a central host. The cost averages around $230 per site for a DSO. We are considering moving to a managed IP VPN network proposed to us by Bellsouth and AT&T. Has anyone else here made that sort of change? I am concerned about reliability and not having to play the “its-broken-but-not-my-fault” game. When my frame sites go down I know what trees to shake to get it back up in a timely matter.

thanks in advance