One-way airflow sounds nice. They do look bigger. I guess the only time I'd really miss having that ability is when I turn my fan off, which is pretty rare, and only happens when I have to have someone in the room with the cab (last time was a satellite installation technician). On the other hand, they look big and even less stealthy than the Doran darkroom louvres. Guess it's six of one, half dozen of the other, for me. If you use co2, I could see one-way airflow louvres as being more useful, so you don't waste any co2 through leaks when your fan is off.

Gonna try co2? I considered it, but it adds so much to the expense and complexity, and I don't sell anything, just personal consumption, so I decided against it. Doesn't mean it can't be done, I know it can, I'm just too lazy and cheap to mess with it just for personal consumption.