Typing on a touch screen and on a physical keyboard are so different (at least for smaller devices like phones) that you can use an alternative layout on your computer and stick with Qwerty on your touch device.
I switched to Colemak a few years ago, and I currently type around 90 WPM ordinarily, and can peak at about 120 when I'm concentrating.
I have no idea if it's just that I've naturally progressed, or if Colemak is naturally faster, but in any case, I was a competent typist before I switched, and have significantly improved since.
>Now it has even been transferred into the PDA (can we just start calling PDAs what they are...which is not a phone) and tablets
I'd reverse that statement, phones are still phones, but tablets are PDAs.
Now it means, "Pocket computer that's usually connected to the Internet."
What's wrong with that?