I used to carry the E2e. When I got a "KL4" bezel to evaluate I was stunned by two things:
1) Regulated output - the output does not dim and yellow like standard flashlight does. This regulated output gives better quality light for longer. A significant advantage.
2) The beam - lots of bright white light - the output is more "flood" than "spot" which is ideal for many applications, typically at close (short) range.
The E2e does better for seeing things a bit further away and because incandescent light is fuller spectrum compared to LED white light, the E2e's beam doesn't get washed out so easily in ambient light (such as street lighting etc).
I suggest that you got for the "L4" rather than the "E2e" first. You can likely aquire a SureFire E2e bezel and MN03 lamp from a CFP Member on eBay - I believe called SureFireParts or something - check out CPF for info.
Since I switched to regulated output flashlights I've not been able to go back. When I do, I tend to use only the cream of battery runtime and swap out to fresh batteries when the brilliance has ended (very wasteful use of SF123As).
I'm sure you'll love the L4.
Al