Ever the optimist that I am, after spending (I can almost guarantee) as much time playing the Theremini melodically as anyone out there, I have come to the realization that quantization can in fact be a pedagical tool for learning how to play difficult passages on the analog theremin. As a beginner, I am convinced that playing in a semi-quantized state can improve your technique.
Now I am not talking about turning the Pitch Correction dial all the way to the right. Playing in a fully quantized state is really more an effect (albeit a useful one if you like to riff on scales - which you can easily do on the Theremini when fully quantized). But you will not be able to jump between notes without unwanted quantization effects. Not at all what you are looking for as a training aid.
But turning that Pitch Correction dial between 8 and 10 O'Clock puts you in a state where you can still get portamento but also a bit of pitch gravitation/correction to the set scale and key occurs. This can let you hit pitches with greater accuracy than you would on the Etherwave especially playing scales, but still maintains a challenge. In fact, it can be quite difficult to play lines in this quantized state without any quantization artifacts coming in to play. If you are too slow you'll hear unwanted pitch motions or motions to pitches you don't want. So in my opionion, it's a great training aid to develop crisp hand movement for note articulation that you can then take to your Etherwave.
Then again, quantization with some practice lets you play real trills and ornaments (something you could never do on the Etherwave). This makes the Theremini a great instrument for Baroque music where you can use quantization to your benefit and also take advantage of limitations in vibrato and great volume differentiation (which are not used to any great extent in Baroque/Early music and in my opinion are the most challenging aspects of playing the Theremini). Frankly, playing Early music on the theremin with a ton of vibrato to my ears just sounds wrong (though most may not notice or care about this if not musicologically inclined).
And of course you can slowly dial Pitch Correction back to the point where you are playing in the analog-like pitch field without any quantization and then head over to your Etherwave. For me personally however, the quantized effects of the Theremini are in an of themselves useful for certain types of music in addition to training so I really see the Theremini as an adjunct instrument that I will go to when I want to play a certain kind of music and head over to the Etherwave when I want something else.
How might this semi-quantized sound be used to my advantage? Well, lets say I have a totally diatonic piece that is in one key. I should be able to dial that up on the Theremini and play some things more easily than I would be able to on the Etherwave (and better prepare me to play them on the Etherwave).
Here's a little example of playing in the semi-quantized state. I recorded a little arrangement of a bit of Bach's "Jesu Joy of Man's Desiring". You can hear a few little quantization gotchas (they almost sound like ornaments and I assume I can learn how to actually play them as such). This is a wicked piece to play on the analog theremin. I just don't hear anyone playing it. My goal is to learn how to play this really well on the Etherwave, and I am convinced practicing on the Theremini in quantized mode will help me in that quest (my Etherwave playing I feel has improved because of the time I've spent with the Theremini). I do have to redo that last phrase but I can guarantee I could never play pitches this well at this speed right now on my Etherwave.