Against rush decks, like ferox and serket, I feel like having SoG in first turn is way better than sanctuary that sometimes you can't play until turn 3 or 4. It's true that sanc makes darkmatter a fair fg and wins alone against decay (specialy if you PA it), but it also costs 3 light instead of playing QT and playing SoG on turn 1. Sometimes you can't use SN until turn 2, so you can save about 10+ hp by playing SoG over sanc. Also, early SoG can sometimes use dark and death quanta produced by QTs, which you don't use for the rest of the deck. Also, having 5 sanctuaries really stresses light quanta, which you don't have a ton early.