Hey - that's easy! Buy 'em both! And go ahead and get a KL1 head for the E2O. Then you'll have a nice EDC light (E2O), and one of the most advanced lights available with a wonderful combination of throw and spill (U2) for walking around. You should carry two flashlights anyway! /ubbthreads/images/graemlins/grin.gif
But seriously - they are very different lights. The E2O, being an "E" series light is highly customizable. You can buy lots of great after-market stuff for it, as well as accessories from SF. It is pretty pocketable, too. It's an incandescent.
The U2 is a lot more expensive, but it's a lot more advanced light. It's like an L5 with 6 different regulated output levels. So since you can mostly keep it on a fairly low level, it is easy on batteries, plus it will take rechargeables. It's a bit larger, though, and probably not as easy to EDC for some people. (I think it would be hard for me to EDC, but others do it all the time.)
If you can afford it, I'd go with the U2, unless you are looking for something to keep in your pocket all the time. (Or unless you have big pockets!) Why the U2? Well, if you can afford it, the variable light level seems like it's pretty darn useful to me, and it's one of the most advanced lights out there. (I don't have one, but I've used other variable output lights, and I think this is a beneficial feature.) It's not a big light, by the way, at least by the standards of a 2D cell flashlight. Compared to that, a U2 is actually pretty small. It's just larger than some of the tiny, yet bright, lights available. It's small compared to my SF L6, which I just love!
The two lights are aimed at different customers, and they are really pretty different lights. It really would not be silly to own both of them. (Provided, of course, that you can afford and desire to spend that much on flashlights. From most people's perspective, it's probably completely silly to own either one of them, much less both of them...)
Hey, you could just as easily go the other way, save a bundle, and get just the E2O. It's a terrific light and it's a lot cheaper. And there are a lot of guys here who will only trust an incandescent light - hotwire's ain't dead!
Hope this helps - your question is a little bit like asking "which is better - fish or chicken?" (Fish - I'm real tired of chicken at the moment.) /ubbthreads/images/graemlins/wink.gif
