Topping off water bottle with snow

Looking at Nippletop => Dial. Long day of hiking. Was going over my water options and thought instead of carrying four liters I could carry 2 and simply scoop some snow into nalgene after each water stop. And carry fuel. I have a steripen so can purify. I was just picturing the usual resupply spots (Gill Brook) and picture thin ice over swift water. Would welcome any thoughts.

I have read the atmospheric pollution thread as well as some great ones on winter thru hikes of NLPT.