Re: Technique, stances and all of the other RULES we need to understand and sometimes ignore...
One of the classes that several of our IDPA club members set up, had Larry Brown, a well-established IPSC/USPSA shooter, as instructor. And he made some of these same points. Larry has competed internationally and held the Grand Master ranking when I worked with him -- which was about 10 years ago. Larry then (don't know about now) was working as an instructor with Special Ops types (Green Berets, Delta, and sometimes SEALS and Marine Recon types, etc.) at Ft Bragg on a fairly regular basis
He said that most of these guys used the Isosceles stance, but they weren't locked into it -- their objectives, whether using handguns or assault weapons or other hand-carried weapons (like sub-guns) was to be flexible and effective. Isosceles was the starting technique, but they could bend, twist, squat, run, etc. and do what had to be done. (That sounds like it might be a combination of ISOSCELES and a variant of the FIGHTING STANCE mentioned above.)
They did a lot of force on force training with simunition that when one of those rounds hit you, it but didn't break the skin. He laughed about one time when he went to the doctor (a woman) about some shoulder problems, and pulled his shirt off, she saw he was covered with small bruises, and immediately became concerned that he had some sort of blood or liver problems. He had to calm her down, and did so by explaining how they came from all of his training exercises.
Larry was (IS) a great instructor who was really good at guiding you in the right direction without attacking your ego. He wasn't there to show you how great he was, but to help you become a better shooter. He ran great classes. I keep thinking I ought to get some additional personal instruction from him one of these days, but somehow I never do it. (I tell myself I'm getting too old to do a lot of IDPA or USPSA -- I'm 74 -- because crawling or getting up from a kneeling position is becoming more trouble than it's worth.)