There's a couple points in this post I'd like to comment on:
First, the statement that Qw or Dv works one hand or the other harder. I think they are actually both closed to balanced over an hour of typing, but when you consider how we type, there's a big difference. Qw makes one hand work a while, then the other, and so on. Dv alternates hands with almost every keystroke. Type this on Qw: only exaggerated stewardesses jump on reverberated pumpkins. Nasty. I think the longest one-handed word on Dvorak is "puppy"
Qw also makes you type by moving your hands; with Dv, you mostly type by just moving your fingers. Qw puts 70% of keystrokes on the TOP row and 12% on the Bottom. You only type on your "home row" 18% of the time. Dv puts 70% in the middle, 22 on top, and only 8% on the hard to reach bottom row which contains the least used letters. Qw also has you jumping top to bottom a lot (try "minimum"). These are called "hurdles" and they NEVER occur in Dv unless you are Scottish. (McGyver - Mc in Dv is where Mi is in Qw)
Concerning Qw's "home" row: why only ONE vowel?? J and K are less used than T and H, for example. F doesn't make the top 10 either. And Semi-colon!!??? Really!
Dv's home row: AOEUI DHTNS keeps your hands alternating and at home. Also, the consonants on the right are arranged for lots of "rolling-in". Examples: TH SH SN ST aND. Try rolling your fingers out - it's harder, isn't it? KJD on Qw is THE in Dv; (3 reaches vs. 0 reaches) which can you type faster?
Here's a good page: http://www.theworldofstuff.com/dvorak/
The other big trouble with almost all keyboards is that they are TWISTED to the left. Why? So the keybars won't jam. But computers don't have keybars. My solution to this twisting of the left wrist and over-stretching of the right hand has been using a Typematrix (typematrix.com) keyboard. Once you've experienced the pleasure of matrix layouts and the easier to reach center-Enter and backspace, you won't want to go back. Another benefit is that the TypeMatrix can plug into a laptop's USB and the board sits exactly above the built-in board.
The other point I dispute is the time required for relearning. Studies have shown that ex-Qw typists can regain their former speed in just 52 hours of training - that's about 26 days (more than 2 hours per day is counter productive). That relates closely to my own experience. After 30 years of Qw, I switched to Dv in 1993. I printed out the layout for training. At the end of the first day, I was up to 20 wpm. In a month, I hit my former speed around 60 and today I can cruise at 75 to 80. If I still had my younger fingers, I could hit 100 easily.
So, is it worth switching? You will almost certainly regain your former speed and will likely exceed it. This is because Dv is so much more comfortable and less tiring. Even at a little less speed, you will be more productive. You are also less likely to have hand or wrist problems as you age. I currently have none.
You have to type on many computers? (sys admin types) You could actually carry a Typematrix around and plug it in. It will work with the original board still plugged in. I've tried it. There are no drivers to load. It just works. It's also hardwired to type in DV or QW or even Colemack so there's messing around in the control panel.