Does anyone think theres an advantage to using the cat6 NE8FDX-P6 over the cat5 NE8FDP?
It all depends on how much movement goes on in the back of your racks.
If you're in there often and for example coiling up a power cable and stuffing it in the back then the PCBs on the older CAT5 connections are a bit fragile.
I've lost a couple due to them taking an impact in transit from something loose in the back of the rack, PCB torn away from the connector.
I think the soldered connections were still fine but the anchors from connector shell to board had gone, they got swapped out once that had happened.
If your racks don't see much change or movement inside they'll be fine.
NE8FPDs are plenty rugged from the outside but the new CAT6 ones are much better at the back.
They're the only Neutrik brand connector I've had that has been damaged in any way in over 30 years (and I must have thousands of various types).
If it weren't for the cost I'd swap out all of my NE8FDPs for NE8FDX-P6s just on ruggedness grounds.