Over here in Australia, if you were showing in a breed class, they would want the horse unplaited (welshes, connemaras etc) if they are a native breed.
But in any open class no matter what the breed it is required to plait. I always show my pinto mare plaited as it gives off a neater presentation. I do rosettes.. They are neater. I think your horse would look stunning in a running braid. I have never seen a horse being shown in Australia in one though.
But where you are, trends are different :) Freakin gorgeous horse!
Cross Country- The act of hurling yourself and your equine partner at a stationary object with poise and grace while attempting to survive...