Find a local BRP dealer that also sells boats with Mercury outboards. It's the best situation for you to find a qualified mechanic that will work on both. My local BRP dealers sells everything BRP from ATV's, sleds, Spyder and boats. They are also a Mercury Outboard dealer. So they have a mechanic for Rotax as well as merc. They are unafraid of my 240efi.
That being said, if something takes the proverbial crap, I am prepared that the parts may be expensive. So far, they have been gold at helping me maintain the motor and keep it in good working order.
Get a good deal, and get it to a dealer to look it over before buying. If you don't have a dealer nearby that will touch it, then shy away.