"If you could devise a way to measure latency precisely exactly rather than estimating it I would be eternally grateful." - GordonC
The guys at Moog could probably tell you exactly. But once it is reaches a certain value it almost doesn't matter what it is, because it's bad. I measured a rise time of 0.1 second, -3dB of 2.6Hz. Who knows where in the signal chain this is happening, or what order it is (1st, 2nd, etc.) but it's bad with a capital B.
I'm not saying the low gestural bandwidth rules it out as a useful musical tool, but in this regard it is distinctly un-Thereminy and cannot be placed fully in that category. I suppose that's my biggest gripe with the Theremini, for some it's a wolf running around in sheepskin (though others will likely not notice nor mind the low bandwidth). To market it as a full Theremin is deceptive.
"The negative impact of the latency of the Moog THEREMINI will increase with the skill of the player. A beginner with little or no knowledge of theremins will probably not even notice the problem. Give the same instrument to an accomplished virtuoso and he or she will probably declare the thing unplayable (as several have already done)." - coalport
This is pretty much what I would suspect. Dabblers generally just slide all over the place, but precision players need to get to the note as quickly as possible.