Absolutely! I've been getting Devacuts for 7 years and I straighten about twice a year just for the heck of it. (funny, before I found CG and Deva cuts I straightened my hair always! 35 years!)
I just make sure I curl it a little with a curling iron after I flat iron it. If I let stay stick straight, it looks a little uneven or wierd with all the layering. The other thing I do is set it on really big rollers instead of flat ironing and that works really well, lots of body.
3B, with some 3C