Looking at upgrading my KZS10's in the near future. Potentially a newer model... KZAS12?
I might even go down the custom route. UE6, UE7, UE11 look promising. I suspect going custom will be night and day to what I'm using now. The UE6 get a lot of love from bass players so not sure if it's worth splashing out for the 7's or 11's?
One thing I've found from the KZs is that they slide around in my left ear during live shows and I'm constantly adjusting. Also the tone it reproduces is quite thin and sometimes low volume, even when I've maxed out on the Behringer P16.
FYI - Going into a Behringer XR18 - Silent stage from now on.