I got the anvil with the integrated stem and the USA. First I used the stem without mouthpiece on a hydratube, the o-ring from the heatshield keeps the anvil in place and it feels like a big a** glass stem. As I really like to RTL the cooling provided by the hydratube wasn't enough (used it dry as cleaning a hydratube is a really painful process) so I started using my megaglobe and I was amazed by how easy it is to white wall it with the anvil. Still it wasn't enough cooling so I started using the USA with a Vong(i) stem and a MJ arsenal mini recycler and that almost hits the spot, until two things happened. First I almost branded myself on the forehead and secondly, as I added a stinger to the stem (I'm on a personal quest to achieve the smoothest RTL hit) little yellow globs started forming in the water. I remembered that the WPA descriptions mentions that it was designed to allow the anvil to have a "full" glass path and prevent condensation. Time to use glass stems with the USA. My obvious first choice: a BB9, but it didn't worked that well because the 10 mm joint of the bb9 doesn't make a tight fit with the minirecycler so I switched to the standard straight 10-14-19 mm multiadapter with the USA. That way I can use the mini recycler on the go and the megaglobe when I want to look how easy it is to make big clouds with the anvil.
So now my questions, how can a WPA be that much different from a USA with a WPA stem? The WPA doesn't have the airflow control but it doesn't seem to need it as posted by other members, can you still RTL with an open airflow?
Is there a reason to get a WPA now other than looks, build quality and that it will make a tight seal because of the o-rings?