Well, if I had a horse that was any harder to fit than Bay, I'd surely consider it. We got ecurbh's to fit because it had so much rock in it, and still we had to make the custom pad to go under it to make sure it didn't bridge. Also might be good if you had to fit multiple horses with very different backs and only one saddle.
We chose ecurbh's for Bay, but it seems to fit Cyn as well. That was just lucky, with the cost of western saddles it'd be expensive to have to replace them whenever you change horses.
I fit into the multiple horses with just one saddle. My Ortho Flex fits Tennessee, who's 17hh and weighs 1300 lbs as well as Blade who's maybe 15hh and 900 lbs. So I can't complain.