I’ve not tried Dvorak. However I have a Maltron keyboard and, although I still use the QWERTY layout it does have its own layout built in. I may be wrong here but I believe that you can hire their keyboards on a trial basis with the cost coming off the final price if you decide to buy.
Comment: I hired a Maltron keyboard with a QWERTY layout. It costs 10pounds per week. If you buy you get half the hire charge refunded. The Maltron people are really caring to deal with. They sent me the keyboard straight away to my home address without a clue as to who I was. I didn’t get an invoice for weeks. When I eventually decided to buy I wanted a slightly different model. They sent me the new one first, so that I wasn’t without a keyboard for any time at all. This meant that I was in possession of two of their expensive keyboards with no security whatsoever. The people on the end of the phone were really pleased I had found the keyboard useful. The keyboard comes with an adaptation course for use in changing from a flat Qwerty keyboard. I wasn’t a touch typist, but took the opportunity to learn it along with the new keyboard. I did 15 minutes per day (which was as much as I could manage at the time). It took me about 10 days to complete the course. It needs to sink into the brain beyond the conscious level. They say you need to give the new keyboard a full month to get used to, and I think this is right.
I think a Maltron is actually WORSE than an ordinary keyboard unless you use all your fingers properly. You also need to be sitting very high up to get the right hand/wrist angle. Therefore unless you touch type your neck is really craning downwards to see the keys. However, a chart is supplied so that you can put this in a better position and look at this rather than the keys themselves. It hasn’t “cured” (ho ho) my RSI but now typing isn’t such a strain. My hands and shoulders still get tired and uncomfortable so I use DNS too and try to take breaks. (Plus exercise and all the other stuff which is now part of everyday life).