I have owned a SF Z2 LED for a while now. It is by far one of the best and most reliable lights that I have owned and was a trusted duty light for a few years in it stock configuration (mind you, mine is not stock anymore). The grip and performance characteristics of the light are fantastic and it is great for night time use and, with properly night adapted vision, provides ample light for most short range uses. The light is made of aerospace aluminum and coated with a Type 2 anodizing to enhance its durability, and it is very durable. The stock beam profile is very smooth and provides a great split between throw and spill for all around practicality. As far as working in smoke and fog; LED technology has not advanced enough to measure up and you will always get better performance with a incandesent lamp assembly for this purpose... period. As far as durability, reliability, runtimes, and overall output LEDs are superior in the Z2 sized package and output range. The problem that I found with this light is mainly in finding carrying options regardless of whether you are using it personally or on duty. Surefire has 3 carriers that will work (V85, V85A, and V70) and Blackhawk has 1 (the Night-Ops Mod-u-lok holster) and thats about it.
However... If you are looking to purchase something in the surefire line I would decide pretty quickly if you want something that uses a P60 module or something that will be brighter then the current "stock" models but will not be upgradable.
The current line features a drop-in module which can be upgraded and changed as technology betters itself (hense my NON stock Z2 LED). Unfortunately this method does not provide "maximum" or "optimal" heatsinking and thus surefire is moving away from the drop-in for its future LED tech.
The New lines (Z2-S, AZ2, S2, etc...), due to start being released on April 1st, 2010, are fully integrated head assembly's to provide maximum heatsinking to the LED. While the new line is going to be a fair bit brighter then the old line, as expected, they will no longer be compatible with after market enhancements from manufactuers such as Malkoff, Dereelight, Thrunite, Lumens Factory, and others.
Anyway... thats my 2 cents. Hope it helps. Do keep in mine that all my experience with this light is from an LE perspective, so without additional info of what you are planning to use this for I really cant give you much more info.
Stay Safe
Alberta-Blue
