One thing I have learned is that if I use the right product and the right amount I can diffuse and not get a ton of frizz from it. The key for me is to let my gel set up before I diffuse.
Thats where the hard hat dryer comes in. Its really speeds up the setting of the gel so I can diffuse to get some volume in the crown area. Learned this trick from my Deva stylist. If you have time to air dry say about 30 minutes and diffuse you should be ok. I dont leave myself enough time to air dry first. I style everyday so a hard hat dryer is a big time saver for me.