I've never grown sativa, but I've read that it can grow over 15 feet tall. You can prune, but if you're going to do that you should just get a sativa/indica cross. That way it won't grow as tall, and the flowering time will be alot less. If you go to most seedbank websites and look at their selection, they tell you the average height of the specific breed you're looking at. Besides height issues, with how high you're going to have hang the light...the lower bud sights won't get enough light and won't produce. So basically you're going spend alot of money for seeds, alot of time flowering, and get very little in return. Again, I think you should go with a sativa/indica cross. Also, I know you said those aren't the lights you'll be using but your thread title is thoughts on my cfl closet. There's a very slim chance you'll grow sativa successfully with cfl's. I had a hard enough time getting a decent yield from LR2's with cfl's, and those plants are short.