Grow cab. Need Critics please asses.

I personally wouldn't change the direction of your fans simply "because your working against physics" . It wont make much difference; go with whatever way best suits your needs.

Interesting. I am thinking of putting some sort of noise dampering on the housing for the fan. I was thinking of acoustic foam, but then i saw some sort of mat system they use to line motor boxes. And it looked similar to what you used.