I don't know if I'm going to make any sense but I'll give it a shot.
Has your guests ever had a souse vide steak before? The reason for my thinking is that a sous vide cooked steak at 129deg versus a steak cooked on the grill at 129deg will both have different consistencies/looks when compared to each other. Maybe your 129deg would be just fine.
Or do i just cooked totally f-u'ed up