https://www.youtube.com/watch?v=711T2simRyI
(I know this is not the only presentation in the existence but it's one that I found; there's one by the author of Plover within some longer presentation about it.)
Honestly, doesn't seem super fast to me :-).
Docstrings, writing documentation, talking to colleagues on Slack, asking questions on stackoverflow, writing mails, browsing, working in the terminal. We spend a lot of time writing. How much time could one save by e.g. doubling the speed?
Another aspect is of the working memory - will it free your brain's resources? Will allow writing at the speed of thought allow for new/more thoughts?
I think we should explore these waters, and steno is a solid choice.
While nobody can deny the fact that most of the time in programming indeed is not spent writing, how about this: you type slower than you can think.
So, when you get an idea, it's nice to be able to transfer the idea to the source code, so you can then move on the next idea or next part of the same one. You don't want to be held back by an inferior input method or a language with a lot of ceremonial about doing simple stuff. This happens in short bursts, even if the total time is quite short.
Sometime it happens so that one thinks faster than one can speak. This usually leads you to get mixed up in words.
A fast way to enter ideas is an important part of developing ergnomics.
So with typing keywords fast and efficient auto-completion, I doubt Steno would somehow make you a faster developer.
Clarity and correctness rules over speed here.
The actual custom typing in code is pretty small in comparison. A few var names that auto complete assists with anyway.
I'm sure there is some gains to be had with using steno on code. But I'd bet there's less a return on code than with English prose.
Steno is good for transcription or taking notes, but it's not great at other things.
You can set up Vim-like navigation e.t.c. too (e.g. [2]), for moving about in code. I haven't tried it.
I think however that the benefits of coding with Plover aren't really great enough to justify the huge struggle it would be to get proficient with it.
[1] https://github.com/openstenoproject/plover/wiki/Dictionary-F...
[2] http://www.openstenoproject.org/stenodict/dictionaries/vim_d...
I think this will be better answered by someone who has crossed that bridge than you simply jumping to that conclusion with no experience or data to back up your claim.