I have one. I don't like to use it. When I exercise my brain is way off in alpha wave territory. I found it harmful to actually getting work done. I go jogging or ride a bike instead.
I came to say something similar, but without the reasoning. I found that when I used a standing desk over a treadmill, the mechanics were alright as I type code (rather than mouse designs). The problem was in the thinking. The level of exercise increased bloodflow but didn't sync with the careful deep thought needed for working through complex/detailled situations.
Reflecting on this thought, I think it's because deep thinking requires/benefits from 'stillness' which is a way of saying free of distractions of noise, motion, etc. Walking on a treadmill I can do the same kinds of work I can do in a not-particularly-quiet open office. I don't know if concurrently burning calories that could instead go into thinking factors in at all.
