I know I don't REALLY need it, but I succumbed to the Xmas buying bug and got myself a dedicated tactical light for my HD shotgun.
Here's the one I picked: http://www.botachtactical.com/intecm3tacli.html
I wound up going with the Streamlight M3 for a few reasons.
Number one: It's NOT integral. My HD gun is also my slug gun, and I'd just as soon be able to take the light off with ease when I go hunting. I like my longer fore end and 4 shot sidesaddle (as opposed to shorter fore end and 6 shot sidesaddle), and I don't want to change out the fore end.
Number two: Price. That Surefire system is nice, but even more pricey than this Streamlight. I got the light and the mount on sale, so I did even better on price.
Number three: Streamlight makes good lights. I have several Scorpions scattered between various vehicles and hunting bags, and they've all been reliable flashlights.
When it gets here and I give it a whirl (now where in the world can I shoot after dark?), I'll get back to ya'll with a report. I'm particularly curious as to how the bulb holds up after a dozen or so slugs go down the barrel.