I have had the Ego T system for about 5 months. I have got two other smokers onto the Ego T system. I have both the A & B type tanks (regular & mega). These have been bought from a variety of reputable vendors. THEY ALL LEAK. That being said they taste good and are pretty convenient. I don't have the time or patience to drip all day. When mine leak it happens all of a sudden, never when their full, and the tank will dump half its contents through the area between the battery and the atty. Noticing this I decided to fill up the tanks when the fluid gets below the bottom of the clear part of the tip. When you can stand the Ego T upright and the fluid drops far enough below that clear window that you can't see it, it is about to cut loose. Following this rule for several weeks, not one leak. Get lazy and break the rule, and it leaks. It is a bit of a pain because you can only enjoy a fraction of the tanks capacity before you have to start dinking with it.
I like the wick and hanging chad theories. I tore apart my first atty today, adjusted the wick, and pulled the chad off of the tank and put it back together. We will see. I am determined to find a permanent solution because the taste is great (smoother than LR and high voltages), the battery life is great, and they are small and inconspicuous in the hand.
Hope this helps.