Lots of people are going with 1.75 tracks now, you'll just have to be a little more consious of your riding conditions and use a scratcher if youre in hard packed or icy conditions.
The only other thing I can think of to consider is that the MTX's have a narrower ski stance, so if your'e into the corner carving, it's going to be a bit more of a handfull. Also, just as sideshowBob said, you'll probably want to gear it up a bit as the top end on most MTX's is around 80-85 mph. I rode an MTX for a couple days last year in the U.P., and had no issues with it in stock form, and actually enjoyed how snappy it was at lower speeds. The lack of 100+mph top end wasn't an issue and would go just about anywhere!