I finally got ahold of an EH Pro Kayfun V3 and man this thing is sweet. Fit and finish is perfect. I couldn't find ANY machining flaws at all. The button head fill screw with washer won't leak no matter how hard I try to make it. THe thicker base and higher position air hole lets the adjustment screw stay recessed and flush when full open so there is no chance of hitting the top cap or 510 connector on a mod like my v1 clone. Even came with an M tank as well as the small clear piece. I sold the M tank to a guy at my local b&m though since the tank looks cheap to me with it on 
I have it set up with a 30g 11 wrap 2mm ID micro coil at 2.2 ohm and cotton an its hitting great. I've vaped 3 tank fulls dry (litterally no juice left but a bit in the wick) and not a single bad hit save for that slightly dryer last hit of the tank. An even bigger plus for this tank for me is NO WHISTLE, unless you have the draw set pretty tight and even then its not obnoxious like my other kayfuns. Definitely worth the purchase.
I have it set up with a 30g 11 wrap 2mm ID micro coil at 2.2 ohm and cotton an its hitting great. I've vaped 3 tank fulls dry (litterally no juice left but a bit in the wick) and not a single bad hit save for that slightly dryer last hit of the tank. An even bigger plus for this tank for me is NO WHISTLE, unless you have the draw set pretty tight and even then its not obnoxious like my other kayfuns. Definitely worth the purchase.