You can absolutely compete in just about anything that allows you to carry, manipulate, and fire your firearms safely. I’ve seen a bunch of guys running in armor. And, I don’t mean “I’m shuffling my feet, but this is a run n gun, so technically any forward progress is ‘running.’” I mean, damned near sprinting from stage to stage. There are guys into this sport every bit as much as USPSA, 3 gun, or PRS.