Another one here that swears by Ultium. My horses have always looked great on it. I wouldn't touch sweet feed with a 10 ft pole. I think you've been given great advice here. I keep a slow feeder net stuffed with good, quality hay in my horses stall. In the winter, when the grass dies down, I put some in the pasture as well. My horse looses his head a bit on alfalfa - tends to be nervous and spook at everything. I replaced it with soaked beet pulp that he only gets in the AM.
"Do the best you can until you know better. Then when you know better, do better."
- Maya Angelou