I learned to type on a mechanical QWERTY in 1967, then in 1986 I changed to a Maltron 3D dual hander, using the Malt layout.
With the QWERTY I could do about 60+ wpm. With the Maltron, as a court reporter, I am able to do 180+wpm transcribing a single speaker. It took me about 6 weeks (using both Malt and QWERTY layouts) to get to 15 wpm on the Maltron. If you put on a blindfold and place your hands on the keyboard, but can't straight away tell which keyboard you're using, then I suspect you are going to find some difficulty because you may get conflicting "kinesthetic memory" feedback. If your primary keyboard has a distinct "feel" as soon as you place your hands on it, it'll be easier.
I can still touch type on a QWERTY keyboard, but I'm down to about 25 wpm, simply because I don't use the QWERTY layout. When I first started using the Maltron I was working as a "temp" legal secretary and I'd take my own keyboard with me. There was some initial hesitation from some employers, but when they saw how well it worked, they were very happy to have me come back later to do more work for them.
The Maltron keyboard is definitely NOT cheap, but I'm still using my original 1986 model, and it's never broken down.