It's way more durable than any mainstream brand lightweight rain jacket, but I wouldn't want to go uphill through over head high alder with it too many times. If you're hunting anywhere off the coasts, vapor is the way to go. Most years you'll hardly wear it, just sits in your pack as a security blanket, so definitely worth the weight savings. Seak is really only necessary if you're doing multiple full days out in the rain every season.
I was in the two feet of snow up high in September last year, and definitely did not need the seak. Even in moderately heavy snow, I just ran chama most of the time. That wool pretty well dries as fast as it gets wet in most snow. But there are times the rain jacket comes in handy for high Western snow, but the vapor is way more than tough enough. Wearing full weight pack, off trail through timber, no wear or tear
Vapor is measured greater waterproof and way more breathable than stormtight. They probably figured if they could get better performance for lighter weight, why not. Stormtight wasn't really intended as an all day every day multiple weeks every year piece anyhow; like seak is. Everybody wants one piece to do everything. In following first lites advice about the use of their pieces starting a couple years ago (one would think they would know best how to use their own stuff), I've come to realize that I'm way more comfortable with way less weight and bulk on myself and in my pack if I use focused, specialty pieces. Generalist stuff just fails to meet the need way too often, and you end up packing around more and heavier pieces to try and fill those gaps.
