There are at least 4+2 atties that fit the eGo regularly:
- The standard 510 atty, with or without gold band. The original one for eGos is the Joye, many of the others are made for unregular 510- or eGo-clones and well, you have to like that. (I don't.) The 510 expert you talk about is most likely one of those. (3.7v clone atties are great on mods, though.)
-- Standard 510 atty with low resistance
- Mega-510-atty, looks just like a longer regular 510 atty, which is what it is
- eGo-Atty, ordinary 510 threading, mady by Joye, comes in two shapes: Cylindrical and conical. The cylindrical (occasionally called "Type B") can hold even more liquid than the conical ("Type A"), 2.5ml vs. 1.5. Much softer than the regular 510 atty.
-- At least the cylindrical one is also available in a LR-version.
All of those need different carts, too.
Added to those atties, the 306 also fits the 510 threading, tiny little thing, thoroughly lousy carts, but vapes very nicely.
Then there are several different cartomizers out there, many for the 510, some for the eGo. Many of them burn their filling, though, and they are more expensive than regular atties. (Because they don't last anywhere as long as a regular atty, usually.) Some taste very good, though. The e2 doesn't have a filling it can burn, as well.
And of course you can use several other atties on the eGo with an adapter.
I've got a few pictures
here, text may be in German, but pictures should speak for themselfes. No pics yet there of the cone-shaped one.