Issues i see
1) What is the expected PSF on the tracks? One of the biggest advantages is the reduction of damage to older roofs by less walking. The machine might also be converted into a man carrying roof device for the same reason.
2) You need a physical bar on the front of the snow grinder, to prevent runing into objects that are out of sight.
3) Seperator to keep gravel out of the hopper
4) better way to get the machine to the roof. Lifting eye(s) are better, easier, and safer.
5) Hopper dump. Needs to lift up and over the taller parrapets, or to a rooftop snowmelter. Enlarge capacity as others have said. what device will make sure the whole hopper gets packed adequately? Maybe a small hydraulic arm compacts it like a trash truck does.
6) Where is the Zamboni attachment? thats what this reminds me of.