Hi Vikki finally you may have grasped my point. You are not a rock coach and your techniques do not really work on rock type voices.
I checked out James Lugo listened to a few of his songs not that much impressed in HIS performance. He is a tad weak and lacks warmth and depth. Do not know what he is like as a coach but reckon he must be OK cause at least he knows the rock type styles.
Steven Memel seems to have the CV and track record and lots of experience but I was un able to hear his voice. He claims to have a different unique approach. If you rate him then he must be good.