I had several phoenix go the trip to leakville. I need to grab replacement wicks to resurrect them, I think. If there's any air in the syringe when they're being filled, they'll leak. The leaking while vaping has to be a sign of over-wicking, resulting in the cup flooding. The air holes are partially the problem, because if too much can be drawn in, perhaps a redesign is in order. Air should be able to be drawn in without liquid flowing out. I wonder if they could introduce a one-way valve into the design, but I don't know. It would certainly reduce leaks, however.
This sort of valve would open when air was drawn through the mouthpiece, then close when the draw stopped. This would probably make the phoenix perfect, and is mainly why I retired so many to add new wicks to. I figure it's worth a shot, though I still think air is pulling too much juice into the cup per-draw and that's why the leaking with vaping happens.
EDIT: I wonder, does this happen as often with the TCs? I would think not, because of the cup's proximity to the liquid when carried vertically, but if the design is similar but flipped, it's quite possible it suffers the same drawbacks regarding over-wicking and flooding when in any other position- horizontal, upside-down, ect.
After all, the BC's airflow is directly tied to how much juice the air feeds into the cup, already submerged in juice. TC's would rely more on the wick itself, and to a lesser extent, airflow.
EDIT2: It may be possible to block the bottom airholes...wait, would it be possible to use a drip shield around the phoenix with a 510-510 adapter, ensuring it was air-tight and raising the airflow to the top-holes of the drip shield? I'm going to try this.