TooManyHobbies:
I shoot 2117's. They're on the heavier side, coming in at 12 grains per inch. I don't know about the other arrow you shoot.
Take the complete arrow weight with head, fletching, inserts, and nocks. At 31 inches that comes to about 535 grains (with a 125 gr head). Divide that by your draw weight of 56# and you come up with 9.55 GPP.
Now the debate starts. Some bow manufacturers will not warranty a bow if you shoot less than 8 GPP. Mid range is about 10 GPP. Personally, I think that your 9.55 GPP is just fine. I wouldn't hesitate to shoot 8.0 GPP, myself - complete pass throughs on Whitetails.