I have several E2O's in all of their original configurations, some with the two flats, twisty tailcap and some with the newer round body and clicky, and some with round body, but twisty tailcap. I have a round body that still has the twisty tailcap that came in the original red box, a few came that way during the transition to the Z57 clicky tailcap. There is basically three variations. I like the MN02 and MN03 lamp assemblies for EDC. The MN03 is basically like carrying a 4D Maglite with better output and that's plenty, plus the quality of light is better with the lithium batteries and orange peel reflector. I have one E2e that I have configured as an E2O. Basically it has the long pocket clip and MN02, but it was originally an E2e. And I EDC several different E2e's with the MN03. It's such a wonderful little light, I don't know if I can ever bring myself to really EDC anything else for lights, I'm old school like that.
Seeing an actual E2O is fairly uncommon nowadays, especially compared to the E2e. I don't EDC any of my E2O's anymore.
Another thing I wanted to mention was that I've noticed it seems that the E2O's bezel length is often slightly shorter than the E2e's. This could be manufacturing tolerances or an actual difference between the lights themselves. I've never really been able to decide if this is a real thing or a coincidence. Just something I've noticed over the years in comparing E2e's to E2O's. The amount of orange peel varies greatly from bezel to bezel in E2e's and lamp assembly to lamp assembly in the larger P60 style lights, so it could very well be due to tolerances.