how wind resistant is it? Would an Arc'teryx Hyllus be worth the extra $$$? (the lifetime warranty makes me want to say yes...)

For my two-cents on the comparison, because the R4 and the Hyllus aren't as close, performance wise as is portrayed. The Hyllus is constructed without a membrane, and therefore,isn't as windproof as the R4, but will breathe better. The Hyllus is designed to be worn alone in medium weather conditions (it blocks more like 70% of wind, and is moderately water resistant) but also cut to be worn as a really warm insulator under a water-proof shell when the weather gets fierce. This is the really appealing part of the Hyllus- it can be used across a wide range of conditions, in various configurations. Both Patagonia and Arc'teryx have lifetime warranties and make excellent quality products, so it really boils down to fit and your intended uses.

At nearly half the price of the hyllus the Patagonia LW R4 will perform plenty well for you. Fully windproof with a killer windproof membrane that stretches incredibly well, moves well with you, and isn't crunchy at all.

Both are fairly comparable. Both are windproof and are water resistant. Similar weight. Patagonia has a lifetime warranty as well and they are very good to their customers in regards to warranty service from what I hear (I personally don't know since I've never had any of my Patagonia gear fail). If you look at the material on each, Polartec says the Windbloc on the Patagonia is 100% windproof and that the Power Shield 02 on the Arc'teryx is 96% windproof while the other 4% supposedly circulates within the jacket but doesn't get through. I think that they're almost identical so really it would come down to which looks better to you and how much you want to spend. I personally have the r4 and I love it and have had no problems with it. Hope that helps you out.