My Orion and Kanati both like the same setup which weighs in at 525 grains, so 10.5 and 11.4 grains per pound respectively. My RER XR likes a stiffer shaft, so I use a 50 grain insert instead of 100, so I end up with 475 grains, which is right at 10 grains per pound of draw. I generally try to stay between 10 and 12 grains per pound. Any heavier kind of gives mixed returns IMO. Beyond 12 ggp the arrows drop WAY faster. Penetration is not an issue with my setup.
Lighter than 10 ggp and my bows tend to be noisier. I will sacrifice a bit of speed for silence any day.