dissss and many others are wrong about touchscreens
In another thread, dissss said this in reference to the Surface Pro 3:
"The thing is it isn’t necessarily comfortable to use on a desk either – input devices are important and touch screens are not necessarily a suitable replacement."
I almost just replied in the thread, but it was a bit off topic to the OP. Also, it is a thought I have seen expressed many other places and I feel deserving of its own thread.
Nobody ever anywhere ever, has ever suggested ever that the touchscreen is meant to "replace" any form of input.
Touch, since its inception, was designed to be a tertiary form of input, after keyboard and mouse. If you want to navigate Windows using only a keyboard, that is viable. If you want to navigate Windows using only a mouse, that is viable. Now if you want to navigate Windows using only touch, that is viable. But Windows works best and really shines when you are given all three inputs as options.
Every time a study is done that shows touchscreen desktops lead to arm fatigue, their methodology is to remove all other forms of input. But look at how people with actual touchscreen computers use them, and you will see that they still use the mouse and keyboard for scenarios where those inputs make more sense, but will touch things whenever they find that to be more comfortable (touching to scroll a web page rather than mousing over to a scroll bar for instance).
So yes, touchscreens are perfectly comfortable to use on desks. Just ask the millions of people who already do.