I've been using for the past season a Simms G3, but recently decided to make the switch and try out the Patagonia Guidewater Vest. Both vests have the same MSRP, $200 USD. The Simms is certainly a very cool looking and well designed vest. I think the website boasts 22 pockets, which never left me wanting more space. I fit 6 fly boxes in there without a problem, as well as all of my other tools and gear. My only downside to this vest is that it never quite felt comfortable. It's molded to shape, which certainly helps the fly boxes fit in their places, but always left me feeling like I was part of a SWAT team instead of enjoying a day on the stream.
The Guidewater vest arrived today, and I was pleasantly surprised at how comfortable it was from the get go. The vest itself feels like you're hardly wearing anything at all. I immediately tried to stuff my boxes and gear in there, all of which fit without a problem. Like the Simms, it has plenty of straps, holes, and clips for all of your tippet spools, forceps and other gear. Both vests also boast a full back pocket, perfect for holding those larger items, which in my case, consists of a bottle of Gatorade, a sandwich and some dog biscuits. The only thing I'm cautious of is that many of the pockets are mesh lined. I'm hoping that they will hold up, otherwise this will be making a trip back to Patagonia. The Guidewater also has curved pockets which are supposed to help with the natural curvature in your body, and they seem to do a good job of that. I'll post up a report when I finally get to fish it. As first impressions go, if I were to see these two side by side in the fly shop, despite the G3's really cool look, I think I would go with the Guidewater.