I wish my comments were more helpful, BUT:
I tried the original mini-protanks, and thought that the metal uptube and mouthpiece just cooled off the vapor too much, and I really didn't like the taste and feel of the stainless mouthpieces (are these replaceable on either the PT3 or the K1?)
Although it might sound bizarre, I really prefer the all-plastic
tanks like the GS-H2, or the Vivi
tanks (NOT the Vivi novas!). I think they give better flavor, a more comfortable mouth-feel, and a warmer vape.
Sorry to not answer your question directly, but perhaps the bump will attract someone who's used both of the tanks you're looking at, and who could give you a more relevant answer!