Yeah, but the M2 costs substantially more. Now don't get me wrong, I don't have a problem selling you one for $112. Heck, I'll sell you three.
http://www.1sks.com/store/surefire-m2-centurion.html
But, I own both and though the M2 has several advantages, including the shock isolated bezel, pocket clip, and Hard Anodized finish, I feel that the Z2 works just dandy as an everyday light.
http://www.1sks.com/store/surefire-high-intensity-personal-lights.html
It's comfortable to use, a bit smaller overall, and even though it doesn't have the pocket clip, it fits well in most pockets anyhow.
SureFire is, in my opinion, the BEST solution as a personal flashlight. And if you walk out of the house with your PDW, cellphone and spare mag, but don't have a light, you are doing something wrong.
If you plan on using a flashlight more than occasionally, do yourself a favor and invest in a recharger conversion kit or go whole hog and get yourself a 8AX (or NX), 9AN, or 10X Dominator rechargeable. They cost a bit more up front, but the battery savings alone make it worth it.
Kevin