I have taken my '08 X-14 from sea level to Park City UT at 5000 feet with no operational issues. The ECM adjusts air-fuel mixture automatically. I make sure I run premium fuel as HP decreases at altitude.
We ski with a family that brings a CSX from Phoenix to Lake Powell for five years with no issues. This is a 600' to 4,000' elevation change.
You may need to check on invasive species inspection requirements as a lot of states implemented new laws the last two years. I have to be inspected everytime I go from WA to ID or to any National Recreation Area like Lake Powell.
Last fall I got a lot of new questions about how I maintain my permanent ballast tanks to make sure I have no milofoil weeds, mussels, etc. at both Lake Powell and the Idaho border crossing inspections. I know our boating friends also had questions on maintenance of their live wells, which were visually inspected.