I switched from qwerty to normal dvorak 5 months ago and have increased my average typing speed from 45 wpm to 61 wpm, according to http://play.typeracer.com
I had some trouble with vim but I'm back to normal vim speed now, without any vim changes; it probably took about 4 months to get my vim shortcut speed back.
I'm now going to try out programmer dvorak as I do a lot of C++ coding.
I use a typematrix keyboard, which lets you buy a blank rubber cover and write your own letters on there. It also has switches to switch to dvorak and colemak modes, without any need for the operating system, but it doesn't have programmer dvorak mode. http://www.typematrix.com/
The keyboard is really awesome and I totally recommend getting one if you're going to change to a different layout anyway. I didn't plane to change to dvorak, but once I got the keyboard, it brought out all my bad qwerty habits (like reaching across the middle), so I thought as long as I'm re-training for this keyboard, i might as well learn dvorak.
The other thing is, you can't go back to the dark side once you've crossed over. I tried running with dvorak and qwerty for a while. I love dvorak too much and stopped qwertying for a month or two, and now I'm like a 2 year old on qwerty.
Update:
So I've been on programmer's dvorak for nearly a month and I'm very comfortable with it. I use caps-lock or num-lock to enter a lot of numbers, but usually just shift for a couple of numbers.
In linux I set up right alt and right ctrl to be the keys that change the keyboard to let you type ñ and accenty things (as I also type a lot of Spanish).
This was done with sudo dpkg-reconfigure keyboard-configuration
on ubuntu.
It is a lot easier to code on programmer's dvorak - in bash, python and c++.
The main benifit I'm finding is no carpal pain after a 10 hour typing session.
Also my average speed is still going up:
Update 2:
I've also bought the nice keyboard: https://ergodox-ez.com/
I've set up my own layouts on it: https://configure.ergodox-ez.com/keyboard_layouts/kzzrbb
I had to move some of the keys around, because the keyboard has less keys than a normal one, but it's good in the end because they're all closer.
The one down side is that I now have two shifts; one to change to layer 2 to type numbers; and another which is the real shift sent to the computer (used for selecting text, etc.) - in the end, with practice, your brain learns anything.
This keyboard and layout is very anti-rsi :)