Headroom, sativa's stretch, and pure sativa's might not stop stretching through their huge flowering times. A lot of indicas finish in 8-9-10 weeks and stay nice and short. Sativa's generally go longer, so you must care for the plant longer. More time for stuff to go wrong. A lot of people that grow sativa's in confined space have to train the living shit out of them so they don't grow 20 feet tall

Sativa indica hybrids have the best of both worlds, shortened flowering times and a little bit of added stretch generally speaking of course.
Personally I'd grab a couple packs of the DNA Limited, I have seen good results with these strains so far also had some myself. 3 packs for the price of 2 is always nice if you go with the attitude promo you'll get more freebies too.