See I think SafeChoice is too high in sugar/starch too. It's 20% sugar and starch where most sweet feed is 30-40%. I also have one choke prone horse so I can't feed pellets.
So I feed Triple Crown Senior. It's 11% sugar/starch, 17% fiber, 10% fat and 14% protein. It has too many calories for my adults so I cut it with TC's 30% supplement. They get what they need without too much sugar.
Having said all this, what you're "supposed" to do per Dr. Kellon the equine vet specializing in nutrition is have your hay tested and supplement to balance your hay and that's it. My hay source isn't consistent and well.... I'm lazy :)
ETA: My horses aren't in even moderate work though I do have a couple young ones. I have no idea really how to feed a horse that's worked hard.