I would like to see more amateurs emulate J.B. Holmes. I have seen too many amateurs with long, loose backswings. This often causes a lack of control, consistency, and power. While a long swing can create power, it only does so if the correct kinematic sequence is performed in your downswing. The proper kinematic sequence in the downswing starts with the hips, followed by the trunk, arms, hands, then club. Amateurs with long swings often want to start their downswing with their hands first, which greatly reduces their ability to generate clubhead speed.
J.B. Holmes has one of the shortest swings on tour, but has regularly been one of the longest hitters. The key is not as much in the length of the swing, but rather the proper sequencing of his body as he turns through the golf ball.