Although I wouldn't recommend the KZ S2's to just anyone, or everyone, I'm really enjoying them the more I use them.
The KZ S2's are persnickety in their BT usage - even stable usage gets "glitches" at times - but if you don't panic you can ride it out and they'll "come back", or require 8 second hold the touch on both to reset and re-bind to my device - required less and less often btw.
The sound is worth it. Turning on "loudness equalization" in Windows for the KZ S2 device makes them bloom and gives a little more headroom to their maximum usable volume range.
I've used them for hours at home to be able to walk around and interact with others, also used them mobile while on brief shopping trips and while waiting for services, and having 2 pair lets me bridge the gap on long excursions - I really recommend having 2 or more of the same TWS for coverage on longer time periods, and once they recharge in their cases you can loop back and reuse them. 3 is a good number, perhaps safer than 2. I may get another S2.
Oddly KZ can't provide additional memory foam eartips, they sent me dimensions and images but say they can't give me the foam tip manufacturer info or how to get more of them, and afaik no more can be bought from KZ. Do any of you know where to get them?