Q: Who are the top competitors in 2015 in 3Gun and PRS matches, the two sports at the top of the food chain in terms of competition?
A; Over half are LE and Mil with excellent service records. Talk to them (i have, at length) about the benefits and or liabilities of shooting high level competition.
Q: Why do numerous LE and mil units seek out high level civilian competitors as contractors to get training and to act as adversaries in their training?
A: Because their commanders want the best for them.
Props to the OP for starting yet another good discussion. I'd like to add a few tidbits.
I have seen many of the "top" SD trainers, even a few on here, shoot in person. Frankly, their shooting skills are mediocre at best. But many had very good tactics. If you have great tactics, you may avoid the use of lethal force. If your tactics suck, you had better be a good shooter!
It is all about the cognitive stack IMHO. What is the cognitive stack you might ask? In general, a person can only hold so much information, and process a limited amount of new information, at one time. When you hit 5 items in the stack (for most) one item will be pushed out. Youth and the elderly have maybe only 2-4 items in their cognitive stack. Animals only have one. It is a relevant topic I discuss in training whether it is a CCW focused or competition focused course.
When you handle firearms frequently, and shoot frequently, the necessity for the actual firearms manipulation can eventually leave the cognitive stack. I do not need to think about breathing, walking or seeing, same with firearms manipulation. When I drop the bolt on an AR, I do NOT need to press check (and possibly induce a failure) because I know how it sounds and feels when a round chambers, and when one does not. I do not try to fire a round with an empty firearm, I instinctively know when I have run dry. OTOH, lack of stressors and lack of time shooting, that person will not know.
When my firearms manipulation and shooting are not in the stack, it leaves room for target ID, shoot no-shoot decisions, use of verbal judo, creation of diversion, aggressive movement off the X, etc. Fill that stack up with the draw, sight alignment, safety off and trigger press...you only have so much of the stack left to process NECESSARY new information melded with your initial assessment.
My SD guns are almost identical to my competition guns. In fact, some pull both roles. I try to do FOF as often as I can as well. FWIW, the worst habits I developed (and had to break) came about from shooting IDPA.