Well I looked into cool tubes awhile back and except for the fact that I already have a good reflector I would definitely spend the money for one in the future. If you get one good fan that would be all you need (a GOOD fan) and you want it to pull the old hot air out, not pushing cool air in.

As far as the rest of the ventilation I really don't know....I have never grown in a cab setup...just a spare bedroom so I will leave that one for someone with better experience on that.

Good luck.