The SureFire x300U is a great outdoor WML, but you might want to run some DRY GUN inside drills before slapping one on your bedside gun. Even without eyes adjusted to dark, it will rebound splash with so much vigor you'll see spots (at minimum) and will be totally night blind (at max).

I like 200 Lumen with a focused center beam and large Nav cone. This works well inside and out to about 250 yards (max distance I tested on my farm).

I have and use a variety of lights because like guns "one size does NOT fit all"....

SureFire M600A with KL4 for room clearing rifle;
SureFire M600C with KX2C for general purpose (might be replaced with M600AA after testing is complete rifle);
SureFire M300 with K1XC for GP lightweight builds;
Streamlight TRL-1 C4 and TRL-3 for all handguns.

The move toward 500-600 lumens is being driven by the same people that like to wear black boots and kick down doors. Real world civ applications (short of high risk SWAT action) yields very different results.

Just as I wouldn't use my SCAR HEAVY for CQB...I would not use more than 200 lumens anywhere except the desert.