For the kind of performing I'll want to be doing, I would like extreme accuracy - I'd like to perform standard jazz, classical and pop tunes with singers and other instrumentalists and I will need to be in tune -- as in tune as the singer or the sax.
(I know this isn't the case with a lot of ways people perform with the theremin, but this is me.)
Like you I have watched a thousand or ten thousand performances; for some of them I really admire the showmanship of the aerial fingering - I know that the performer is moving much more, and more dramatically, than is required to make that music.
To me it seems like for the time being, I need to sacrifice showmanship for accuracy - and hope that at some point I'll be good enough to flamboyantly wave my hands up, down, sideways, and wiggle my fingers dramatically, and still get the right pitch.
This goes for my expression hand, too. I see many really great performers beating time with their expression hand or moving it in a way that in no way affects the loudness.
Do you feel the same way? Do you end up being able to play more dramatically as you improve generally?