I have been using one of those for about five years and love it. I switched to a track ball about 10 years ago when I started getting pain in the tendons on the back of my hand using a normal mouse.
I've also got a keyboard without a num pad meaning that I don't have to reach for the trackball - it sits where the num pad would normally be - and that stopped my right shoulder blade clicking which used to happen when I rotated my arm over the num pad for the trackball.
You know, stuff that everyone else just doesn't understand.
Simple questions that they don't understand and don't like it when that fact is highlighted publicly.
On the flip side: Being a decent software engineer doesn't make you a good web developer. I've had to deal with a site built by decent software engineers who didn't understand the web and it fell seriously short in SEO, content management, analytics, degradation and a slack handful of other stuff that's second nature to a decent web developer.
As long as we're going to reinvent the wheel again, we might as well try making it round this time. - Mike Dennison