I know Fontaine/Ravens but I don't think they are making steps anymore. Thats about all the aluminum trailers makers out here anymore.
I own a Mac flat and love it, my dad owns 2 Reitenouirs and loves them. All of them have been good trailers but we don't know much about the stepdecks.
East has a fixed drop, and it's designed for 22.5 tires. It would look aweful funny with 17.5 tires on there! I have one(east step with 22.5's) right now. Good trailer methinks.
Wilson makes an aluminum trailer, but again only for 22.5's.
If you have never had a low step something you should consider is ground clearance, you will rub the frame once in a while, usually backing down into docks. Don't know how aluminum will hold up dragging on asphalt. Combo with steel frame may be better.
Back in the fall of '08 I was considering a tridem with 17.5's so I had my Wilson dealer spec me a new combo step. The third axle added $6,000 and ~2,500 lbs.