I do carry a white infinity, Surefire D2 and a white photon on my keys all the time when I am at work. I use the photon the most, If I have to work on something in the dark for more than a sec or 2 I take out the infinity, it is easier to hold in my teeth while I work. Also it will last a lot longer than the photon and the battery is easily replaceable.
When I am not at work I usually only carry the white Photon and somethines the D2, although now I am starting to carry a 2 AAA mini mag with the Brinkman nexstar lamp, way smaller than the D2 and darn bright.
Brock