My biggest want w/ a multi-touch monitor is one that can lay at an angle to the desk - sloped more or less like a mixing desk. Vertical touch is a pain. I bought the 21.5 inch dell that you can slope from vertical to almost horizontal, and it is great. I've got a bigger screen on the shelf above, and I'm finding I seldom look at it anymore, even when I'm using the mouse.
I'd be wary of any touch monitor that couldn't do that trick, unless you want to get a swivel mount for it.
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