I've been using my own edit of a German and Swedish Dvorak keyboard layout for three years now.
As both at work and at home, I have a Windows PC, I was able to import the Keyboard Creator File I had created, and do not need to switch. For my Apple devices, unfortunately, I could not find a way to to import it.
If it's for work, you should ask the responsible (IT?) if they can install your keyboard layout. If you tell them you are more productive this way, this should work out fine.
As for occasional keyboard usage, I think you should use your QWERTY from time to time to stay fit and get over that phase when you mix up some of the keys - there will always be situations when you may need to type a few words on a QUERTY (a friend's computer, an internet café, ...), it pays off to be flexible.