I've seen customer configs on MPLS networks that just ran BGP to the provider edge MPLS router; and I've seen customer configs where GRE tunnels are built between sites over provider MPLS networks. I was hoping to get some opinions as to people's thoughts regarding the need to tunnel over provider MPLS networks.
In fact, I have not mentioned security, just plain GRE.
As I said, if MTU/total efficiency is not a concern, I would slightly prefer tunnels.
Just setup a single multipoint tunnel interface with the appropriate map or nhrp statements, and run you favorite routing protocol on it.
No need to coordinate anything with ISP so it's simpler. One thing you can ask, if if they support jumbo frames :)