XXtrasuns are my personal preference. With 2X 1000w You could easily get away with 6" snf s 450 CFM fan. If you went to 8" you would almost be doubling the CFMs through the lights 8" @ 750 cfm............
8" hoods are a few inches taller so if height is an issue, steer clear. I like 8"s because they move a lot of air.