ZYX Sigma vs Diamond vs VDH Cilibri XGP

Hello,

I recently acquired a Bergmann Magne TT and am using VDH Colibri XGP. Altough this combo sounds wonderful, the upgrade bug led me to the high end ZYXes.

Can't find much reviews however on these cartridges. So my question: did anyone had the chance to compare the ZYX Sigma and Diamond?

Thanks