OK, neighbors here I go...

[performance]

Kevin,
Good to see you here.
I'll preface this by saying, from my years growing up in heavy equipment, you don't find Caterpillar using much short arc welding on things like backhoe booms, loader bucket pin bosses or undercarriage cross bars. Every thing like this is spray that I know of. They have some of the top metallurgist in the country and some very particular metal types. If spray was an issue, they would not be using it almost exclusively. This is in steels mostly of course...but the action/mechanism is basically the same in steel, stainless, and aluminum, though the current and voltage values at which it occurs may vary.

Much of my "schooling" would contradict many of your statements, though I guess a lot of it is opinion interjected too by various instructors. I've heard the same concerns said about short arc with porosity and weakness. When you think of true short circuit, the wire is actually breaking and melting after it contacts the metal and the arc is extinguishing at that moment of wire contact and that would seem to increase porosity and weakness. This is happening many times a second. This effect can be observed or "magnified" by turning the wire speed up too high while keeping the voltage low, in the short circuit range. While this may exaggerate the action, it does give you a slowed down look at what is happening at a smaller scale within the weld.

With spray transfer, the arc cone is doing the melting and the pinched off droplet is delivered to the puddle via the force of the arc itself. It arrives already at a fully melted metal puddle and blends right in.

The arc cone with short circuit is minimal and irregular which reduces penetration and thereby increasing the chances for defective fusing as the wire literally stubs in and out of the puddle, which is typically quite cool by comparison.

As far as wetting in, spray mode itself wets in far better, in fact so well that it is not good for out of position use without a few tricks up your sleeve like pulsed spray or STT.
But the biggest concerns I have ever heard of was that of over penetration and HAZ creation. Perhaps the bend tests you saw failed because slow travel speeds and a large HAZ in heat sensitive material. I am not aware of those tests and have seen nothing in my research to point to those tests you refer to.

Globular transfer is really a no man's land and not desirable in the least as it is more unstable and spatter-y than either short circuit or spray...sort of like an aircraft being buffeted just under the sound barrier before it breaks through. You get good penetration, but the violence of the arc can introduce defects even though it is going plenty deep.

Now, in spray mode, the droplets are definitely visible and though they are rapid motion, the eyes can still detect it. If you cannot see the droplets, then the metal is beginning to vaporize. The droplets are roughly the diameter of the wire.

Here is a detailed "treatise" that deals with many of the issues you raise. Lincoln has far brighter minds than I that write this stuff. Some of the math is over my tired head tonight. If I had a doctorate in metallurgical engineering, I'd not be sitting here tonight. I know, a lot of people that will bristle and stand against the common and studied science of the matter, just as people believe in inventing a machine that creates its own energy to run with power left over. But I am not one of those guys. Push science to the limits, yes, but stay out of it's way because it will always come back to trip you up. Maybe we are speaking a little different welding language here, but talking about the same thing and that is not uncommon in our industry. There are as many dialects of welding lingo as there are of any language. But referring back to the source documents keep us speaking the "king's" English.

As far as the comparison to TIG and globular transfer, I'd have to say that if your filler wire is melting with a large molten drop before you get it to the puddle in TIG, something is wrong.
http://www.spagweb.com/v8mini/tech_files/welding.pdf