I'm not sure I can contribute a lot to helping you qualify the two, but my oldest DD's team (U16) also participated in that PSPL league. Their coach normally encourages them to play for their HS team, but several of the girls decided not to play this year and he also wanted them to continue to train/play together as he's planning on prepping them for a tournament this summer.
I didn't notice much difference in any of the characteristics you mentioned between the HS players vs. non players. Of course, everyone was playing and training with the club team, so the example isn't the same. One thing many of the girls mentioned was that, "player X never seemed to play as well for her HS team as she did the club team."
I'm certainly no expert, but I try and pay attention to what people who are have to say, and it seems like HS focuses so much more on direct athletic style of play (by virtue of having such a short instant season) that the skills and quickness used more in club soccer might not be exercised as much. Obviously, those are gross generalizations and there's exceptions in style for both HS and club teams.
Overall, I think that PSPL league was good for the girls. It certainly was more entertaining to watch than the HS games I sat through. I think that CPT Fire team was the main driver behind the league, and I know our coach was pleased, but I'm curious how the other teams and families felt too.