This is a great thread Curt. If you don't mind I will share my experiences, they totally concur with yours.
I am lucky enough to have access to great turkey hunting. I have been a part of maybe 40-50 turkeys shot with traditional gear (I can count 39 and I know I'm missing a few). Like most people, we always aimed for the wing butt when we first started hunting them. That was the "common knowledge" at the time.
I have shot them myself with broadheads that range from a narrow two bladed Grizzly, to a big three bladed Snuffer, to a Bullhead, Simmons Shark, and large 4 bladed broadheads. I have personally hit them about everywhere you can hit a turkey, and unfortunately lost way too many (which is easy to do in the Colorado mountains or the brushy, hilly country of Nebraska). I have not lost a bird in a few years now, and I attribute this to being more picky on my shots and my broadheads.
Common themes I have observed:
-Shooting them in the breast makes for very "iffy" chances of recovery, at best.
-Taking out a leg has resulted in 100% recovery rates.
-Larger broadheads do work better.
-Keeping an arrow in the bird makes me feel better, but I'm not certain that it is a necessity.
-Aiming for the wing butt is not reliable. If you hit them there they can die within seconds, but if you hit the actual butt, where the bones all connect, you might not even get an inch of penetration.
My broadhead thoughts (due to success rate and damage):
-Bigger the better. I have killed them with a Grizzly, which was just what I had set up for elk/deer at the time. But I don't hunt turkeys with small two blades anymore. The WIDE Simmons Shark is the only two blade I use these days.
-I love big, wide 4 blades.
-I like large three blades.
-Simmons Shark, my experience - 100% success, 100% keeping the arrow in the bird, and 100% of them dying within sight.
-Snuffer, I've never seen so much damage, it has ruined some meat.
-Bear Razorhead with bleeders, I've used them a lot because I have a lot of them, I always use the bleeders, and while the main broadhead is razor sharp, I never cared if the bleeders were sharp. That has worked very well.
-Any large 4 blade
-Any large 3 blade
-Magnus Bullhead, until this weekend I never seen a bad experience, now I've seen one...
Shot placement:
-One word, HIPS. Shoot for their hips and you have the largest margin of error. Looking at the diagrams that Curt posted confirms my theory that if you shoot straight up from the legs, at just above beard height, from any angle, from any position the bird is in, you will get vitals.
-The higher the better, as long as it's in the body.
-Facing towards, or facing away shots have led to immediate death, 100% of the time (in my experience).
-Strutting toms are super difficult to pick a spot on. Their body is just so much smaller than it appears when they are strutting. If they are facing away I shoot for that big ten ring. Facing to me and I aim for their beard or just above it. I don't like broadside shots on strutting toms, but if I feel it's now or never, I shoot for the tops of their legs.
Like always, I am in a constant search for more information, and while my experiences have led me to certain beliefs, they are all prone to change with adequate evidence or other experiences.
This is a great thread.