I switched to a variation on Colemak because I had used qwerty so long touch typing with left hand and pointer/ring only on the right that it was uncomfortable trying to learn to touch type from the home row.
I'm hesitant to take up any of those because not being able to use other computers seems like too much of an impediment.
I can still type just as fast as I could before I switched on qwerty keyboards. I left my laptop keyboard qwerty and just switched my external keyboard to Colemak so I swap somewhat frequently depending on if I'm at my desk or on the couch/out of the house.
I switched from QWERTY to Colemak about two years ago. When I had first gotten fully adapted to Colemak, and my typing speed in Colemak got up close to where my QWERTY speed had formerly been, my QWERTY speed took a big hit (down from 80 WPM to around 20 WPM). But now, two years on, I can touch-type QWERTY fast-enough (around 60 WPM). I kind of have to establish for myself a QWERTY context by starting to type while looking at the keyboard.
Colemak changes relatively few keys from qwerty, especially compared to Dvorak. I use colemak full time and can still touch type qwerty reasonably fast.