Well, I took the plunge with MB2TM and bought a Microsoft Trackball. This is the first one that I have ever owned, and OMG I love it. It is so easy to use and it just makes sense. I wish that Apple would make a trackball.
m$ generally makes really good hardware for computers. i had a pair of m$ headphones that worked great and had ridiculous sound for their size. any m$ mouse that i have had has been very good and sturdy. they also back up their products with one of the best warranties in the market. the only reason i switched mice was that i got a razer boomslang for my gaming, which is pretty much over anyways.