An NFL quarterback's helmet choice wouldn't matter much to anyone way back in the dark ages (think 2010).
Concussion awareness has changed the dynamics.
Kolb is switching from the Schutt XP to the Riddell Revolution Speed Classic model, a version of the model that received five out of five stars and a "best available" rating in safety testing by Virginia Tech. The Schutt helmet received three stars and a "good" rating. Schutt has challenged some of Virginia Tech's methodology, according to a detailed piece ESPN's Gregg Easterbrook put together last year.
Concussions have sidelined Kolb for portions of the past two seasons.
Some helmets with lower ratings could, in theory, suit an athlete better than higher-rated alternatives based on fit.
I'll update this item with information on what some other NFC West quarterbacks are wearing as I'm able to confirm the information.