One CAD users perfect mouse is another's nightmare! Here are my thoughts:
The freedom of wireless is great but I hate having to think about charging it/new batteries. This isn't a as big a deal on modern mice, so it the concern might not be that imperative. Also there is a small lag with a wireless mouse. CAD lags enough on it's own, I don't want to add any more. However, with CAD lagging you might not notice the wireless mouse lag!!
A few extra buttons on the mouse can be a godsend. I have programmed mice buttons for Ortho On/Off, Osnap On/Off in the past. That works great. Anything the reduces the amount of time or effort in my workflow is what I want. Most extra button mice need separate software to program and run, but most are simple enough to handle.
Ergonomics is huge. My CADMouse from 3DConnexion was one of my favorite mice ever. It was hefty enough and it fit my hand perfectly. It was extremely comfortable and smooth on its movements across my desk. It died. I was (am) sad. I suggest you try before you buy if possible. We use this mouse for 8 to 12 hours every day. A non-fitting mouse can damage your hand, wrist, arm, shoulder, etc. I am considering getting a "vertical" ergonomic mouse so that my arm isn't twisted all day long.
These are the things I look for in a CAD Mouse.
Brian C. Benton
bbenton@cad-a-blog.com
http://CAD-a-Blog.com
twitter.com/bcbenton
www.facebook.com/CADaBlog