Ccoolee,I've made several and it is definitely a love it or hate it concept.
My personal opinion is that the theory works BUT IT IS NOT DRAMATIC.
Based on the way I smoke a pipe, I find the smoke to be a little cooler and a little drier.
I put a Delrin liner in the expansion chambers which makes them super easy to clean.
My original comment on this thread.
Delrin works.
Chas.