The two stage driver for the E1B is in the head, so when you move the head to other bodies, the hi then lo function remains. And keep in mind that it is designed to run off a single CR123 primary, so it shouldn't go on a two-cell body. I don't see much to gain by putting the head on an E1e body, except for cosmetics or if you want more knurling. I use a Z68 tailcap on mine from time to time, but the light spends more time with the stock tailcap because it's momentary is so easy to access without the shroud and I have other lights I prefer to use for tailstand/candle mode. The beam diffuser is a great add-on as this light, with the TIR optic, is pretty narrowly focused.
The E1B is an awesome light.... I love mine.
