Re: Few questions guys
Purging is usually done when the smoke gets harsh as stated above but also when the flavor starts tasting "a bit off" otherwise known as stale tasting. I find this helps to keep it fresh and full flavored.
Height doesn't seem to be as big a factor as the make does. I have an 12" Chinese Pumpkin, 18" inch Chinese 2 hose with auto seal (Both Chinese are crap, they have a real tight pull, used for camping trips and such) a 29" MZ, a 30" MZ and a generic Egyptian at 36" (estimated) I find that the MZ's and the Egyptian smoke the same.
Hope that helps.
At my age being cynical and sarcastic is just making small talk.