Smooth is ID only like Axiom and like Axiom are a pretty good bang for the buck. I can't seem to remember nor find on the Net the info I came across a number of years ago when I was looking at treadmills but Smooth is the ID version of one of the main players in the market.
I had second thoughts about buying something so large and heavy from an ID company, pretty hard to ship back on your own if you really don't like it.