I tried the Flatcap - I mean dealer demo - with my XS2. Small improvement noted. Concluded it wasn’t really worth the expenditure.
My dealer then added a pre-loved HiCap2, for comparison. (Cost was a little less than a new FC). Which, to my ears, sounded like a significant improvement. For example - in detail, bass control and image. Needless to say it’s in my system now.
So, that another idea worth considering?