The major difference between London and not-London is the likelihood of change. An operator in London can buy a set of blinds for his company (probably even his garage!) with the current routes on it, and include any which are likely to come up for tender in the next few years that he wants to bid for, and any destinations for proposed extensions or new termini. (Metroline, for example, seem to have different blinds for different depots and a lot of the newer buses at PB were already fitted with "HIGHBURY BARN").
Outwith London it is common for routes to start, stop and alter with much greater frequency. They are re-numbered and re-routed on a regular basis. LEDs therefore give operators flexibility as the only thing required is to have somebody go around the fleet the day before the service changes and upload a new file to each blind.
(First Mainline inherited some ancient ex-London Darts, probably about 10 years ago now - they had some London style blinds made up for the routes they intended to use them on. Of course, they ended up on any and all routes. You would occasionally be waiting in the town centre for your bus and one would turn up - the driver would go up and down the blind looking for the destination required, then go into the saloon, pull an advert out of the holder, scribble the service number and destination on the back and throw it in the windscreen!)