That's genius! I've tried using it with just the WPA as a mouthpiece, but it got too hot. I never thought to add a reducer to it, I'll be trying this out soon.This is the mouthpiece i use now, it started when i was using my water tool then i popped a reducer on there and it turned out to be a great mouth peice.
Its just the cfx WPA with a reducer to 14mm i like that it looks kinda like a box mod. Keeps things cool even for the short length no burning lips.