I've been touch-typing Dvorak for over 15 years. I was touch-typing Qwerty before that. There were very few situations where I felt that I needed to be able to type really fast, when typing only Qwerty. I switched to Dvorak for efficiency reasons -- not needing to leave home row as much. At that time, Colemak wasn't really an option -- certainly not a default option in the OSes that were commonly available at the time. I've been working in IT for almost 20 years. I have not found my switch to Dvorak to be much of a hinderance, even though I can't fully touch-type Qwerty anymore, but most every keyboard in the States has labels for Qwerty, so re-orientation is easy.
Luckily I don't have any sort of RSI. I have had tired hands in the past, but due to evolving nature of my jobs over the years I never needed to type for 8 hours continuously. i would always have breaks due to being interrupted to help someone, or needing to get up from my desk to deal with a problem elsewhere is the building, or surfing pages for research, or just writing notes/drawing diagrams to figure out a problem.
In recent years, after touch-typing Dvorak, I've started to customize my layouts -- not so much the alphabet, but more like how I need to hit various symbols, functions, or macros. This is the reason why I love building my own keyboard -- I get to customize the hardware and the software to how I want, and over time have the option to evolve how I type, and what I type on.