I agree with most of your list. I am a HS head coach and I also coach a select team over the summer. I do so because of the differences in the game. I do not dislike HS baseball, but I agree times have changed. I have found myself preparing earlier and earlier for my summer team.
I will say this about summer ball though. I am not sure how many coaches want to be there or how many are there because it is something to do with baseball. I cannot tell you how many times I looked over in the other dugout and saw a coach with his eyes closed (I know he was hung over because I was at the bar with him the night before...lol
That is not to say the majority of select coaches are like this, just an example of a few. HS coaches seem to be more "invested" in their team.
With that being said, select ball and HS ball alike are a lot of fun when the coaches seem to be "going at it." I like competing with the other guy and I find more of that in HS ball than in select ball.
Anyways, I like the comparison and I am sure there will be additions to it.