I have the new KS10 and LOVE them. Especially the rechargeable feature. I put them in the charger as I am going to sleep and back in the morning. I have used mine 16 hours a day with no discharge failures.
NO NEED TO REPLACE BATTERIES! I used to hate the ding-dong sound that the batteries were dying. NO MORE!
The sound is better than KS9. Also, tap my ear when the iPhone rings and I am online.
If any con is that the tiny openings where you replace the wax screens are very small. I have had several clogs. But it is really easy to replace them. Get a nice pack and super easy to replace the screens.
I have a three-year warranty.
I have a few cards on “brown batteries” and am giving them to my friends who are still with KS9