I don't know of any risks in changing the MTX fluid, although someone else may know... MTX's don't have valve bodies and all that other stuff that can fail. If you're having problems shifting, your synchros may be starting to fail, but a fresh change of fluid along with some friction modifier (check the FAQ section) should help. Once the search function is back up and running I would suggest looking through the Transaxle forum for discussions on different fluids and their effect on shifting; there's some really insightful stuff there.
