Re: As I only live a few miles from The Hill...
Anyone who believes the fairy story that buying capacity from two different providers ensures your traffic goes down different paths is living in la-la-land. It is not unusual for both providers to buy capacity form the same third party, and so on (it is turtles all the way down).
Indeed. Buy a service based on the service description, and the SLA. If you want diversity (aka route seperation), then buy a service that offers it. Some are even regulated, ie BT and a minimum 3m seperation along the entire path.. But that can result in some eyewatering excess construction charges.
Otherwise it's like you say, and play pot luck. Unless you're renting a specifically defined path, circuits can and will usually get regroomed, negating any diversity/seperacy.. Which is going to be.. fun for GTT and their customers given GTT's acquisition spree, and large presence in the wholesale capacity market. Integrating and optimising all those networks will be keeping their planners/designers & ops people busy for a while yet.