I agree with all that has been said. The E2 is much better because it is so much brighter, yet not that much bigger at all. In some respects, the E2 is actually easier and more comfortable to handle because it is a little bit bigger. For me it is just about the right fit in my hand, where the E1 is a bit small.
I think that the big advantage of the E2 is that it can be taken anywhere due to its size, yet it is bright enough for any use. There is really no situation that I can think of that the E2 would not be bright enough for. Not that the high power lamp would not be appreciated, but that extra power would always come at the expense of runtime.
I have had my E1 since it came out and I still carry it everyday over the E2 just because I hardly ever use a flashlight on a dialy basis to begin with. There are situations though where the E1 is just a tad too dim. I can always more than make-do with the E1 while camping etc. or even for defense, but the E2 has never left me wishing for more output, while occasionally the E1 has.
Hope this helps,
Bucky