Thanks for the comments fellas. I'll be using a 400w hps (55,000 lumens) for 4 to MAYBE 6 plants at a time. Ebb n Flow system with carbon filter and air-cooled hood all exhausted via 1 435cfm fan. Both of my rooms will be exhausted to 1 of the vent ports in the roof. I just made a box-like structure sealed off between the studs of the roof....so both veg and flower will be exhausted to this box (2 vent holes) and the enclosed box (I'd say its about 2.5 ft by 1 ft) has access to a screened off vent that leads directly to outside. I'm HOPING that I don't get any backdraft from the 2 different fans that may or may not be going at different times [435cfm for flower, 160cfm booster for veg]. I do happen to have speed controlls for both fans, though.
The flower room is about 75% complete - I just have to hook up and install the table/flood system and make another light proof barrier just inside of the swinging closet door.
Pics to follow soon.