I can drop a bit on Dvorak and for anybody who's interested.
If you're really enthusiastic about keyboard layouts and keyboard design, then you should probably learn Dvorak and/or other layouts like Colemak and Workman and such simply because you'll find it fun -- hard work, but fun. Similarly, if you care a lot about the feeling of typing (like you're collecting keyswitches and such), then it's almost rediculous to not be well-versed in a second layout (if for anything but the fun of it). Otherwise.... there's not really anything in it for other people.
Personally I started using Dvorak because I needed to break a lot of bad habits really quickly. My home row was Shift+WAD and JIOP/arrow keys, one of my thumbs anchored itself awkwardly on the front edge of the keyboard, and over the course of a year I was starting to get a really burning in my wrists after typing (noting here that I'm 20 years of age and an aspiring programmer, go-figure). Learning a proper, clean way of using the keyboard doesn't get rid of the build-up of pain, but over the course of two years it's far milder. (Because of this, I also use a 42-key Atreus keyboard so I don't have any far-reaching stretches when I type.)
If you want to type more productively, then learning a new keyboard layout isn't for you -- unless maybe you want to get into stenography, but that's a whole separate skill. Faster typing is a product of practice, and a new layout is going to set you back with a 100 hours of awkwardness. Then there's the technical problems: changing your keyboard layout is a native function of Windows and Linux and BSD and such, but all the default shortcuts for programs are meant for QWERTY, not all of those shortcuts are re-mappable, and some programs are going to ignore your OS's selected keyboard layout and will try and parse the keyboard scancodes with their own half-assed methods. Depending on whether or not you're using a native Dvorak keyboard especially messes with this stuff.
The final note I'd like to make about this is that after using Dvorak full time for a month, I completely forgot how to type in QWERTY. To other people I'm like this big computer expert, but I sit down in front of their computers and I have to stare face-down into the keyboard and type with one or two fingers.