Kevin - I haven't tried it on my gasifier. But I did build an aluminum smelter last year and used a pretty big shop vac (one of the bigger craftsman, 5 HP I think). It turned out to be overkill, big time. I had to choke it way down to keep from melting the whole shop.
On my charcoal gasifier, I just use 1 bilge blower, like Wayne uses. It seems more than adequate in that application.
I think Matt is on to something with using the smog pumps, if you want something pretty bullet-proof that is going to have a long life.