Oh I thought the Kayfuns were leaking as well that was really the only reason I have been avoiding the Russians and Kayfuns. I have a couple 22mm mods and a 23mm mech as well.
Real kayfun don't leak unless overfilled or the coil is to close to the air hole. Ive had some clones that never stopped leaking and some that are nearly as good as the real one.
Aqua and expromizer use the same system they are solid too when it comes to leaks. Taifun is pretty much leak free too.