I've become a little wary of the Sherwoods following problems I had with two SR-1 second stages. I found both a little, "sticky," for lack of a better term, on the performance adjustment. Initially, I could go through the full range of adjustment and not have them free flow, and on occasion they would go part way through the adjustment and start free flowing. At a minimum, after each day of diving, I rinse them, while pressurized, and hang dry. When I'm not in such a hurry, I let the pressurized stage sit in a bucket of water for a half hour or so. When not having the problem I mentioned, they have can be fine tuned to requiring almost no inhalation effort which I really like.
I dive primarily with an Apeks XTX-100 and it has performed without fail. I like the way the Sherwoods breathed but, I like the Apeks better. If you go Apeks, the differences between the XTX-50, XTX-100 and XTX-200 second stages are largely cosmetic with the internals being the same. They do come with different first stages. I selected the one with the XTX-100 for its solid one piece body which, intuitively I would think to be the most reliable. My nephew just bought a Mares Abyss 42, which I'm looking forward to trying out. As I understand the Abyss 42 is the nearly same as the Abyss 22 Navy, however the Abyss 22 Navy has a different finish, and better cold water diving performance characteristics. Were I aware of the Abyss line when I bought my Apeks, I would have given it series consideration.
I think the Zoop will serve you just fine and do everything you need it to do. I don't see any need to spend more for recreational diving. I agree with Bubbletrubble on the trying the wrist version. I find it that a wrist computer is easier to monitor while doing an air sharing ascent. I'm for anything that leaves both hands free.
I've been a Zeagle fan for many years. I own a Zeagle Ranger LTD but rarely dive it anymore, simply because the ripcord weight system is not very conducive to weight removal demonstrations in training. For most diving, I've gone to a minimalist setup with a Hogarthian BP/W rig which was a little uncomfortable on dry land at first, but I've come to absolutely love in the water. The Express Tech has an attractive entry price, but once you've finished outfitting it to your liking, you may find you've spent just as much, or more than, as going with a preconfigured Dive-Rite, Halcyon, OMS, Oxycheq, or DSS BP/W setup to name a few. I've found Zeagle quality to be superb.
My Zeagle has a TUSA Duo which is similar to the Air 2. My mode has been to donate my primary and breathe off the Duo. I think it's unlikely that you'd both have ever have to share the Air 2. In order for that to happen, your buddy would have to be OOA and your primary second stage would have had to fail. I could be wrong, but that's the only scenario I see that would warrant sharing an Air 2. The Duo by the way, IMHO, is crap. The Air 2 and Duo both use a different size LP hose quick-disconnect than those used with standard inflators. Forgetting this fact has caused me and other people I dive with problems when borrowing/renting gear. My preference is for a quality octo which I donate first, not depriving myself of air by switching out the reg in my mouth.
