Well, my experience with the Advance Model X is not quite the same as others. The packaged tips will not give me a seal, not even close. So the treble is ear shattering, without a seal. Went to the tip bin and due to the asymmetrical ear canals I happen to own, went with a spinfit in the left ear (medium) and a Sony hybrid in the right ear. Even with that, treble was a bit too hot so I EQ'd the treble down a very small amount and the lows up a similar tiny bit. Now, they sound fantastic. I own the MTW, which to me still rule the BT buds I own or have tried, but they should. I have the QCY T1s too, and they are great for $28, but a giveaway to a friend or relative. I owned the Sony true wireless buds (WF1000x) and the Nuheara IQ buds, returned or sold them. Too many dropouts for me at the time (maybe firmware has fixed the Sonys by now) and the IQbuds were not as good as the Senns to my ears, so I let them go.
Now, the hassle factor is I must remove/replace the tips every time I want store the Model X in the case. Not horrible, but not great for using them on the road. However, they are keepers as I do like the sound, albeit with EQ using the KaiserTone app.
So I'll keep the Senns and the Model X, and that's enough true wireless kit for me. For now.