One significant difference from Cat 6 to 8 is grounding. Though Cat 6a has it.
B
Go Cat8!
I just changed my Maicord Opal Cat6 which was no slouch in its day to an Onti Cat8 from AliExpress, linking the Etherregen to my InnuOS Zenith Mk3: Shazam, cristal clear treble, vibrating bass and an enormous increase in the recordings‘ ambience and liveliness. It goes to emphasize how important the short bit of cable between switch and server actually is. Highly recommended, the Onti Cat8 is a heavy gauge, heavily shielded cable with state of the art magnesium connectors.