A friend convinced me to try dvorak years back, and it was neither a frustrating or annoying experience. Since I can't prove a negative I can't say that it has prevented RSI, but the wrist pain I was beginning to experience when I started learning didn't progress, and went away shortly after I began using dvorak heavily.

An interesting note about switching layouts: I'm a sysadmin, and spent most of my day at my desktop remoting into other systems. Most terminal emulators and remote desktop apps rely on the local layout, so I type in dvorak for those sessions. There are a few, like the VMWare management tools and Dell remote KVM, that don't. I don't notice the difference anymore, and I naturally switch to whichever layout is appropriate for the window I'm currently typing in automatically. The only difference is that I type faster in the local desktop & windows using dvorak.