For example, I do searches of the codebase constantly while coding, so I imagine I'd be reaching for the keyboard a lot anyway since there's no way a gamepad could compete on efficiency when doing something text-heavy like a search.
Think of it thiis way. You type with 10 fingers right and each can give an on or off signal. With a PS/3 controller you loose 4 fingers for holding the device. Still the thumbs are tied to 14 bits per second movement sensors + a button. Then you also have movement sensors and so forth and two fingers or more have analog input. So the bandwidth is there really. Also what you gain from more buttons you loose in movement time and errors due to Fitt's law.
And notice how I haven't gotten into Valve's "knuckle controllers" or glove solutions yet.
If you are interested I'd love to work with your particular use case and problems to get a working solution that suits your particular needs.
http://tbf-rnd.life/ or mail me at trbefr@protonmail.com