I have to disagree on most points. I don't care for "skinny" strings, as I've found no real advantages to them and a few disadvantages...but for the rest...
I don't care for over-built either. 18-20 strands of BCY-X or 8190, 12 strands of Dynaflight '97, 14 strands of 8125 all give a similar diameter string that isn't really bit or really small.
The feel much better on the shot to me, reducing hand shock in any bow that has it. The shot feels more..."crisp", for lack of a better word.
Endless works just fine, if it's made correctly. I make both and shoot both endless and flemish, and have shot both on my Journey. Properly tuned, I can't tell a difference other than the looks.
Performance gain isn't the reason I use and recommend materials like BCY-X. They are more durable, more consistent, and make the bow feel better at the shot.