Update 3-13 just shipped.
Andrew has a special need for a high performance fan so Kurt did some testing on the ES6320 without any duct. The results are impressive. The fan pulled 8005 CFM because it has less static pressure when the 8 feet of flex duct was not used. His fan is scheduled to ship Monday March 13.
You can see a video of the performance on Vimeo here – https://vimeo.com/207813576