Thanks for the replies. Haha the bigger the roots the bigger the fruits, I like that.
I think I'll go with the 7's then. I do have a perpetual type thing going with 2 rooms, so basically I take clones a week before they go into flower, then I veg./ flower for 8 to 9 weeks and do the same thing over again.
I guess I was worried the 7's might be excessive. I've seen people with a similar setup as mine use 7's flowering under 1000watts but I was unsure about a 600. Thanks again!