Just thought I'd come back much later in the thread and give my input now that I've had this tank for a while. I had some issues with it after my post a few weeks ago. I think I was either cutting the slot a little too wide, or I might have been using juice that was too high in VG, but I was seeing a lot of leakage. The sweet spot seems to be either 90/10 or 80/20 PG to VG. It seems like the VG has a harder time wicking through the slot instead of just dropping straight down through the connector, so I found that the less VG I used in my juice, the easier it was to avoid the leaking.
It's also been kind of a pain on occasion getting the O-ring on the top seal to stay centered. It has occasionally bulged out to one side, making closing the thing a pain in the .... Fortunately, I think I've gotten it all properly worn in so now it works like a charm for the most part. It definitely works great as far as getting the juice into the carto, and slotting my own is a very easy process as long as I don't go too wide. Haven't had any dry hits except for when I had it inverted for an extended period of time.