Thanks everyone! Also, T-Dux replacement coils are live, so you can pick those up. We got a small batch before the holiday, and there's many more on the way. Also, there's 2 types of coils. With the one that's up on the site right now, the coil sits in a ceramic cup. The second version, which should be up on the site any day now, has the coil surrounded by a paper-like sheet. What I've found through testing is this: the ceramic cup coils produce better flavor and have a smoother draw, but tend to leak if you use a thin liquid. Not always, but sometimes. Out of 5 coils tested, only one leaked, and the liquid was water-thin. The second type of coil, the "carto-coil" has a draw much more similar to a cartomizer, and it has the paper surrounding the coil, like a carto. This coil mutes the flavor a little bit, but it's basically leak proof. I tried it with the same thin liquid that leaked through the ceramic coil, and it did not leak once. I also tried both with 100% VG, no nicotine, no flavoring. The ceramic version wicked perfectly, even when chain vaping. The carto coil tasted a little burnt after about 5 drags, chain vaping, but was back to normal after 10 seconds or so.
TL;DR If you use a very thin or PG-heavy liquid and find that the ceramic coils leak, try the carto coil. If you chain-vape thick liquid and find that the carto-coil tastes burnt after awhile, try the ceramic coil.
For the vast majority of juices, either coil will work great and it comes down to personal preference. I really only ran into trouble with very thin or very thick liquid, and in either case, I just had to switch the type of coil I was using.