I have a few PT2s and one PT3, they would occasionally leak until I put the airflow control valves on them. Just upgraded to an IBTanked today, so they will probably not be used too much anymore as this blows them out of the water, in terms of flavor. I have noticed Kanger's coils seem to have QC issues, and quite a large percent of the ones I (and my friend with a PT2) have used either leak bad or don't last as long as the rest.
But, to the point, the airflow control valves made all the difference in the pleasure derived from the ProTanks. And on my iTaste VV3, the PT3 delivers a real good taste and ....loads of vape, but the flavor on my new IBTanked with the Smok carts is so much cleaner it is surely my new daily driver.