If you're willing to put in the time to learn a whole new keyboard layout then you should be willing to put in the time to change any default shortcuts that you don't like!

But personally I haven't found them a problem at all, even in Emacs.

Cut/copy/paste is annoying for about a week, then you're fine. Here's my learning curve: http://www.superjoesoftware.com/temp/dvorak.png

I think now (2 years or so later) it's between 90-120 depending on how many typos I make.

You aren't really going to be super fast with dvorak but I do notice that my hands don't feel so tweaked.

I wouldn't say hard, but it can take me a few minutes to get back to full touch typing. Before switching to Dvorak Type 2 (plus <Alt Gr> + homerow mapped to <[({})]> for programming) I did already have to switch between QWERTZ (German) and QWERTY (UK, sometimes US) on occasion, which may have prepared me for it. Though the differences between QWERTZ and QWERTY are pretty minimal compared to Dvorak.

When I switched back (from Dvorak to Qwerty), I was faster than ever.

When you relearn the old layout, you can avoid your bad habits.

Personally I find it damn near impossible to use QWERTY after going to DVORAK, even after several years. As for someone else using my machine, well my friends refer to my work machine as having "the klingon keyboard". Handy for keeping people the hell outta your workspace though ...