the fingerings of the Mountain ocarina is very close to the Recorder
or the penny whistle or the fife. That was what made me most happy. Same fingering (not counting the idle hole) so I can play back and forth between them at will to try new things. The MO stays with me at all times so I can try something during the day and then when I get home take out the penny whistle or fife and not have to figure it all out again. Practicing with one kinda counts about 80% toward practicing with the other(s). I'm so glad the MO is a transposing instrument.
Update:
Confirmed. I've been playing with my MO for two days now. A few minutes ago I picked up my penny whistle again. Much easier than before. Sounds a bit better too. I like playing with it now. Since it can go up another octave using the same fingering as the lower octave it's very useful for figuring out the MO. If a song needs to move up too high I just play it on the PW and see what note I'm playing, then drop to that octave instead. When I have it figured out I go back to the MO.
Sigh. Guess I'd better order the music course from Karl. I'll get a Poly-C too. Darn you, Mr. Karl! You are forcing me to learn new stuff and my brain hurts!!

(Hurt me! Hurt me!)