What is missing here in considering Patagonia's 'greener' products is the fact that the company, from the top down, is trying to lead by example. The company isn't acting under the assumption that their products are going to make a world of environmental difference, only that someone, somewhere has to start acting responsibly. They are also attempting to pioneer new practices, materials, and production methods to be a more responsible company and in, Mr. Chouinard's own words, "Do the least amount of harm". He's hoping that this will inspire and empower other corporations to take the same path, as some manufacturers have started to do with organically grown cotton.
As for the question at hand, I would answer yes, with conviction. If I'm given the alternative between two products, one lighter and one more sustainable, both equally capable of the task for which they are designed, I'll choose the more environmentally friendly option. If it means sacrificing functionality, or, as was stated earlier, less safe, then my choice may differ.
Why? Simple: its the right thing to do. Lately, there is a LOT of discussion about the environment and mankind's impact (or lack thereof) on it. So far, this has cheifly taken the form of rhetoric and sloganization moreso than anything else. We constantly hear words like greener, carbon footprint, and environmental impact. However, little sacrifice is being made by us as a people and very little sacrifice is being asked of us by our leaders. I guess my decision is based as much on this as it is my desire to make an actual environmental impact. I believe, like Chouinard, that someone has to step up to the plate.