I do a fair bit of fox hunting at night. I've tried a few lights for this, namely the budget Ultrafire WF-008 recoil thrower from dealextreme, a Solarforce L2 with the XR-E R2 emitter, smooth reflector and 28mm aspheric lens from dealextreme, and the Solarforce Pro-1.
The Pro-1 is the best of them, by a clear margin. It will out throw the other pair by maybe 30%. And that's running a single 18650. Running the extension tube and two 18650's would give it a greater advantage again.
The Ultrafire and L2 with the optic are for practical purposes about equal. The Ultrafire doesn't focus quite as tightly as the L2, but the L2 loses a bit of oomph through the cheap lens. I am only using a .17HMR, so my shots are generally limited to about 150 metres, which is just about the edge of the effective range of the Ultrafire and the L2. You still get eyeshine much further out, but clearly identifying the animal isn't really possible. The Pro-1 would let me shoot to about 200m I feel, though it's outside the effective range of my rifle.
The Pro-1 will light a coyote up at 200y.