I daresay most mark bugs
devices end up on the classifieds because of the touch sensor. In order for the touch sensor to activate, there has to be some moisture in your skin. There's a popular spurious idea that licking your finger is the only way to get a WA to fire. That's lazy and weird, but that's what sellers of these
devices wish to trade away.
I've got an apprentice that will probably never see the classifieds until I give up
vaping. It's very well built and quite an efficient use of space. And apparently I don't have the dry skin problem plaguing so many others. Check out the apprentice 18650 next to the p+ 18500:
Both are excellent devices. Truth be told, I still use the p+ more often than the wa. But someday I would love to see David combine the diminutive size of newer devices such as the apprentice and caravela with the superlative aspects of his p+ line.