It is the negative pressure and the patented dual pass internal scrubber system that makes all the difference. Not to mention the cabinet it quieter than your refrigerator and all systems are internal lolTo be honest mate, this looks pretty damn good, especially if there is no light leaks, thats a huge problem for most cabinets. No light leaks = no smell I was really keen on getting something similar myself except it was 5k and leaked light in every direction. I would definately go for something with good height (minimum 5 foot for 400-600w), it will help greatly with heat issues.
And thanks for the positive impression