I have one. Yes, one slot. Not a big deal for me cause I also have an X5 II. Wasn't aware that it ran so long. I also have a small FIIO amp paired with it. Even picked up a slick leather sleeve for it. Anyway, I find I use the 5 much more often, so I'm thinking of selling the X1 with amp and case.
Edit: mine is a version 1. Sorry.