In crossbows, Excalibur recommends 350 grain combined weight for all big game. I don't feel comfortable with this, and I'm shooting about 430 grains for moose. This is with a 20" bolt, and I'd guess a longer arrow for a vertical bow would be heavier if the same weight shaft were used. I shoot aluminum, and have yet to shoot a moose with my combo.
I'd think a heavier weight would perform better on an animal like a moose with its thick hide and hard bones.