Hi
MPLS is the transport protocol-set and not the "service" you are getting from the provider.
The "service" is L3 VPN or L2 VPN (VPLS)
L2 VPN is just great if you need to extend L2 VLAN from one office to another.
L3 VPN the provider is taking part in the routing of your prefix.
L3/L2 work just fine and scale in the same way (in the new type MPLS routers).
I will use VPLS because you can move from 1 provider to other without playing with the IP layer & the service is transperent to the user.