I live in the PNW and use the AJ spey hook in both #5 and #7 for summer fish and have not had a hook open up. However, in summer I use 8lb tippet and if I horse a fish, it will break the tippet if it decides to take off.
I find the AJ spey hook in #5 to be a very good hook for low water spey flies and even carry a few royal blue and red spey flies on them in winter for when we get a freeze and the water gets low, clear, and cold (in the low to mid 30's). I've caught fish to 13lbs on the AJ #5 in the low, clear, cold conditions just mentioned and did so on my 16' T&T rod with 12lb tippet with no probelm. I just have to remember not to horse the fish or the hook may bend or open up.
The #7 AJ spey hook I use only in the low water of mid-summer to mid-fall and use it tie spiders and light wire Spade's finding it too short and small for a spey fly to look right.
I use the AJ spey in #1.5 and #3 for spey flies in winter and the #3 during the early summer and later fall as well as during very early morning and very late evening in summer low-water. In fact, I use the #3 more than any of the other sizes during winter. I also use the #1.5 for marabou spiders for winter fish. And the #3 makes for a very nice bunny leech hook and it the hook I use for the fuchsia bunny leeches I tie and fish for chum, and I've caught chum to 22lbs on it without a problem. I also use the #1.5 for some full dressed, married wing classics I fish in winter because I prefer the smaller wire it is made of over the heavier wire of standard salmon irons, which results in fewer flies lost to logs or rocks.
I use the AJ blind eye #1.5 for dee flies that I only fish during winter/spring. I haven't used the AJ #3/0 because it has such a large gap that there is too much probablility of damage to smaller fish like Dolly Varden, although when the return eye is opened up and straightened out, it makes for a very nice, long dee on which to tie double wing dees.
The heavy wire AJ spey hooks I use only on G.P.'s because the standard wire AJ's don't have enough mass in the hook bend and point to keep a full-dressed G.P. riding properly in the water with the hook point down, while the heavy wire ones do. I tie them in both #1.5 and #3.
For standard winged flies, Ally's Shrimps, and Irish Shrimp flies, I use either the Daiichi 2441 or the 2141 depending on the time of year. In winter I use the 2441 only in sizes #1/0, 2, and 4 and almost exclusively for Ally's Shrimps is several colors for my own fishing. In summer fall I use the 2441 in #4 and #6 for Ally's Shrimps I fish in the heavier water on a floating line so they sink a little instead of being in the film. The 2421 I use in #4,6,8 for summer-fall fishing and usually only tie Ally's Shrimps or Irish Shrimps on it for my own fishing.
The Daiichi 2131 (Ververka's low water hook, or AJ's River Dee Low Water hook) I use for dry flies (except Bombers, which I put on Daiichi 2220's in #2,4,6) in #4,6,8 and for true low-water featherwings (the body is only 1/2 of the shank with tail, wing, and hackle reduced in size in proportion to the body) in #4,6,8 with #6 being most common.
The Daiichi 2151 (also known as AJ's Steelhead Iron) I use exclusively in summer/fall and only in #8,10 for tying Spade in several colors, which are fishing on floating line.
I wish Alec had a blind eye AJ spey hook in both #3 and #5 on the market (although I've told Alec many times since before he put the #1.5 blind eye on the market that the #3 would be perfect for larger speys) because both would be perfect for spey flies. If you open up and straighten the eye on these, like Steve Gobin has done for years, you get the same thing. It would just be very nice if they were available already made this way.