I'm running the Billet. Its night and day difference from the stocker. If your not aware, B&M now owns Hurst.
B&M aquires Hurst Shifters | Miscellaneous Blog & Discussions at Hot Rod Magazine
GMM and B&M were the first shirters for the Monaro. GMM was consistantly favored over the B&M by many. B&M seemed more difficult to install correctly as people had problems with stuff coming apart. The GMM doesn't have a real short throw and some complain about the hand coming close to or touching the radio. The GMM doesn't use a linkage, it goes direct to the tranny, probably a plus for positive feel, but a negative for noise. For a short shifting GMM, you need to add a Lou's Short Stick to it and by then you're in Billet territory price wise.
I don't know anything about the Hurst performance, but looking at the pics, I'm happy with the Billet. The springs in the Billet are stout. When I first installed, reverse almost required two hands. They loosen some, but my wife doesn't like to drive it cause its to stiff for her. I love it, the rubber feel is gone, shifting is like "click, click". Downside is some tranny noise under acceleration, but maybe I just need to move the stops on the shifter a touch.
