Isn't the MATS document public domain?
IMHO you are right about transits not usually saving a lot of time. It's probably the lack of a service to the pilot that is a bigger problem. You have to remember that in PPL training one is taught to reveal one's inside leg measurement to every possible frequency along the route. Couple this with another old time PPL favourite - dead reckoning - and you have a recipe for plenty of CAS busts.
The more long-distance pilots just load up the GPS and fly with a listening watch. Unless they make a fairly obscure c0ckup, they should not bust airspace, and they don't ask for a service unless it's radar.
The French have it more right. They don't have an RIS/RAS to VFR traffic, but it's fairly obvious that everybody on the radio has a radar screen in front of them, and they will pass you traffic info if they think it's worth doing.