The E2L AA and the E1L have essentially the same brightness (maybe the same head) since both are designed to run on a maximum of 3v. The E2L (2 x CR123a) runs on up to 6v. I'd found mine was equal to my Surefire L1 (current generation) rated at 65 lumens by Surefire. Which means the E2L on high really puts out about 100+ lumens.
The only reason to get the E2L, if you have the E2LAA would be if the langer E2LAA won't fit in some pocklet or pack your light just has to fit in, or you have a whole pile of CR123a batteries you are just dying to use up.
I've asked Surefire on several occasions to switch the E1L and E2L over to neutral tint emitters. High CRI emitters would be even better. They probably are just not able to source a sufficient number of either to meet their speccs, and/or they don't beleive most people want them.