Welcome to Geekhack.
I can't fully answer your question because I only use an Expert Mouse but can at least report on it.
I've used one for about 3 years without any mechanical trouble. I've heard about others having to clean their trackballs often and can say that in spite of all the dust I subject my office to I've only had to clean under the ball twice because of erratic response.
After sloping and tilting the placement of the Expert Mouse on my tray, I've found it very comfortable to use. Whenever I use a conventional mouse my hand goes numb almost immediately.
The scroll ring is very convenient. It isn't real smooth, something the Slimblade design may have improved on, but the only thing I find annoying about that is that there may be something out there better than what I have.
The button surfaces are showing their use. The coating on the more used buttons have worn through to the black plastic base color.
The rare times I use a mouse I do find it faster to use but the ergonomic benefits and the smaller area required to use it trumps the mouses superior speed for my needs.
If I had to buy another, I'd probably try the Slimblade. I think the scrolling system may offer a better experience and the other features appear to be similar.
