Yup, I've got that exact model for about 6 years, it's one of my favorite pieces of equipment, holds up to a full 100 lb bag of oats and is a well made, very consistent seed spreading machine that sure beats a hand seeder. Several friends have them as well, they're a bit expensive, but well worth it.
They make a variable speed model which would be very nice, and that would control your width. I'd say mine spreads clover and brassica seed about 16-20 foot total width, no way it spreads 28' wide with anything.
I use an 8 penny nail to set the gate width for clover, and a 16 penny for diakon radish, and about a quarter inch for grain like oats and rye. I made one alteration, I welded a 1/2" bar to the bottom to protect the plastic propeller and motor wire connections when you set it down.
Don't spread fertilizer with it unless you clean it well because it will rust away very quickly.
I am intending to fashion small adjustable plywood side shields on each side of the spinner with small U-bolts to limit the spreading width for seeding grass seed on logging roads.