We haven't received our shipment of them yet, and I absolutely don't want to steer you wrong. Give us a shout when it's in stock! We'll have had a chance to look them over thoroughly and test them in our binding release testing device, then we can give a detailed answer.
Hey Niko, they should be able to stretch pretty well in both length and width, and it's somewhat your preference! The medium will probably fit you well, and you may even fit in the small if you wanted something more snug.
Hey Paul, they're very similar! Same shape and profile, slightly different construction. The Alp Tracks LT 84 is a little lighter weight and is full Karuba wood, while the Vertex-X was Paulownia + Poplar wood.
Here's a link to compare the two: Alp Tracks LT 84 vs. Vertex-X