I had a rev 3 Vertical Mouse that I wore the bottom edge off of and then the cursor started drifting on its own. I replaced it with a rev 4 and I love it as well. Helped both my wife (she had a rev 2) and I with our repetitive stress injuries.
One side benefit is that when folks come to your desk to show you something and try to grab your mouse, they almost always pull their hand back and let you drive because they're intimidated by it. It's really not hard to operate, but folks think it looks complicated I guess.
The Logitech MX1100 has many programmable buttons, one of which is part of the thumb rest. It is a right-handed mouse, and this button is actuated by depressing it with the outside of the pad of the thumb. This button works well for me as the "enter" button, but is programmable as double click. There are a two more buttons directly above the thumb that are actuated with the ball and/or pad of the thumb; these work less well for me, so I guess you'd need to feel one in person to see if they would suit you.
The mouse itself (rev 4) is roughly 3.25" tall. If you can comfortably fit your hand vertically in that space, it may work. You do need to tilt the mouse up in order to reposition it, so you'd need a bit of extra space.
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I'm using the Evoluent 3 and love it. Solved my painful wrist issue almost immediately. It does do the double click with the thumb in WF4, no problem. But I am also using a 3rd party mouse control, so I can't confirm it's out of the box functionality.
I agree with the other comments about "other" users being intimidated by it, so it has the cool factor also. I would also say that it only took an hour to get used to.
I bought it with my own money (as opposed to company purchase) and have zero regrets whatsoever. It is also ~3-1/4" tall