I love the v2. Yes, it has a long 510 but it works fine on most mods. I use it on my Doomsday, HexOhm v2, Stingray, 4nine, Paragon, Nemesis, XXIX.....It fits flush on all of those. No issues with the top cap after removing the top o-ring.
Mine pretty much stays on the Doomsday mod. Its a great atty.