Well, a chart in a book I have says that corn sugar is 1.036 SG per pound per gallon of water. Maple Syrup is 1.030. So I guess if you multiplied the amount of corn sugar you usually use (5 oz?) by 36/30, that give you a reasonable amount for maple syrup.
Bottle conditioning: Robust Porter
Drinking: Saison Dupont clone, tripel
Coming soon: Columbus APA, Rich Red ale