They can be "interesting" in a crosswind. Power on the downwind engine seems to help. I don't have enough time in shortbodies to comment intelligently, but the longbodies aren't any worse than any other airplane, once you get used to them.
I'd be surprised if anyone went to the trouble to RVSM a Mitsi...they're not a particularly high-flying airplane. Happiest in the low to mid 20s, in my experience.