The designer says this.

The total cross-section of the cutouts in every dampener plate is bigger than the cross-section of the fan outlet.
So air-flow wise, the box should handle it.

I am considering paying him to have a redesign and order one for testing. I can post the heat results and then if they seem good then people can order from him thru eBay. Low power is an option but it's like owning a Ferrari but only putting it in first gear.