Hi OriginalityIsDead and welcome to the wonderful world of
vaping. I've only been vaping for just over 7 weeks and have been using MT3S BCC's and have had very little leakage. If I overfill, them some gets into the mouthpiece, but I am getting better at not overfilling. Also, I've got a stand for my gear and use a couple MT3S' at a time (with different flavors). The one I am not using, I set in my stand, but put it in with the mouthpiece down (coil up) and have had no leaks.
I also have a small amount of juice in the battery connection area and the folks here stressed that this was normal and to use something like a Qtip when I change out batteries for charging. So far, everything has been working well and the only unexpected leak I encountered was when I did not re-tighten the coil after cleaning (at 4am wake time) and it left a small space when I put the clearo back together. Now, I make sure the coil is tight every time I switch after cleaning. It is amazing that I seem to learn more from my mistakes (or remember them more) than when I do something successfully the first time. So I've learned to remember to tighten (but not over-tighten) and that Qtips are my friends.
This is a great forum and I hope you find the folks here as friendly, non-judgemental, supportive and helpful as I have found them to be. It is a wonderful community.