Update - based on info here I bought a FP Switchback Pro - it has easily replaced the Gunnison as my favorite. Lots of room, comfortable, and just plain EASY to use.I also use three different packs, or, at least I have three but really only use two. Left to right are the old Double Haul, the Gunnison Guide, and the Summit Sling.
First, I'll address the Summit Sling that I will part with soon - it's a great sling pack, and I find the size and organization to be really useful, however, it just doesn't do anything for me that the Gunnison doesn't do and I find the Gunnison more versatile. I bought the Summit to compare against the Gunnison and the Gunnison wins so the Summit is out.
Regarding the Double Haul - it's an old design and is the first pack I bought years ago - prior to that I used a necklace and pockets. The Double Haul consists of a chest pack and backpack that can each be worn separately or together as a unit. For me the chest pack is really good in fit and function but just too small to be perfect. It's great for a quick hop down the creek, and has a good layout where main tools have a place and are in easy reach, however for a longer wade session I find the main pocket too small (and I pack relatively light) which invariably leads to things falling out which leads to me leaning over to pick things up when of course the dang pocket is open which leads to, well, you get the picture. Lastly and importantly, the neck sling places the pack at mid-chest which is the perfect position right where my eyes and hands converge. With the backpack attached, I can haul anything and everything for a long day on the river including lunch and a jacket. In sum, although the chest pack is small, I use it as a minimalist pack and add the backpack for long days thus this is a keeper for me.
The Gunnison is my Goldilocks. It's not too small, not too big. The Gunnison holds everything I need for a day on the river with the exception perhaps of the lunch and jacket that the Double Haul will handle, yet, the Gunnison is not too big to be intrusive. Although some people don't like the weight of a waist pack on their hiney, the this pack does a really good job supporting the weight across the hips and waist AND you can wear the wide neck strap so that the pack functions almost like hybrid waist/sling pack. Organization of gear is EASY - there is a logical and easy to reach place for everything. The front fly shelf is handy and well thought out. I am hard on gear and will pick apart poor functionality yet the Gunnison is top notch with no real drawbacks from my perspective. Wait, there is one drawback. The net sleeve on the Gunnison is a pain if you intend to swing the pack around to the front to work, which of course, is the whole purpose of the Gunnison. The result is that you swing the pack around thus swinging the net right into your work area/face. As such, I carry my net on my side suspended from the waist belt.
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