Hey, I found your other post, its in "new posts" right now.

Anyway, first off, go with the 2 x 600w. Two 600s are far better than a 1000w. Not because of the extra 200w but because they are more economical.

I think your set-up is fine regarding your extraction. If you have a speed controlled extractor fan just turn it up a few notches.

I also grow in a tent. I have 190w LED and soon I'll have 260w CFL. All in a 3' x 3' space ! My 4 plants will be blown away !