As far as I know it's probably the most expensive too...but in my opinion you get what you pay for and I believe that the extra dollars it costs buy enough extra quality/warranty to still be considered high value.
The Streamlight units are nice, cost less, but don't quite reach the same quality bar that Surefire does. I have no experience with their customer service so I can't comment on that. Streamlight does pretty much own the rechargeable duty light market, so they generally have their act together...it would also be a fine choice.
However I personally believe you should also take a long hard look at a dedicated unit like a Crimson Trace...that way you don't have to keep your light on to take advantage of the "flashbulb" technique.
If you buy a laser for defensive use, you really need to take a low light/no light class from a respected instructor, as otherwise it will be truly wasted on you. I don't care if you're a longtime LEO/competitor/whatever, a good nightfighting class will be eye opening.
Vickers, Hackathorn, and Lamb come to mind but I'm sure there are plenty others offering good low light classes.