Although my E1 w/KL1 is brighter than my Arc LS I like the Arc LS better because it is smaller and much easier to carry in my pocket.
I also like it because I can use 2AA rechargeables if I want, increasing the size to what the E2 w/KL1 is.
The Arc LS is designed to run at 3v and the current 400mA version does this nicely, running for 2.5 hours in regulation were the KL1 @ 3v only runs 1.5 hours in regulation.
The KL1 on an E2 does much better at 6v, running in regulation for up to 4.5 hours. But this is even bigger to carry.
The problem with the E1e is the clip is always in the way so you can't get a good grip on the light without repositioning it & it's very awkward to press the tailcap switch without your fingers getting in the way of the light beam. The E2 is a perfect fit in my hand but again, it's twice the size of the Arc LS.
Wow! The poll is 50/50!