Man, I am glad I am reading this because I was about to do a 9 fan sandwich. This will save me a ton of room. Would running this in series with only 3 fans still be enough airflow?

Also, if I am only using three fans connected to a sunbeam rheobus, what fans would work well? I am more concerned with having enough CFM at load than I am with noise, because I can always turn the fans down when they arent needed. I have some 1900rpm Scythe Kraze fans right now and these things seem to move a lot of air.