We have GP90 connected to Navnet VX2 radar/plotter, Furuno VHF, Camino AIS by each data port on the GP 90, without problems.
Our Camino AIS is connected to the VX2, also without problems, except that initially we had to get a software upgrade for the VX2 in order to handle the AIS sentences. This has all been working fine for years.
Furuno UK confirmed to me also that the date rollover issue will not affect the transmission of accurate position data.
As far as I can tell, the date is not used anywhere, except maybe for VHF DSC call, which we don't use - there is no DSC service in the South Pacific.
So, I doubt we will have any problems.
AND I quite like the old Navnet VX2 system - it's reliable solid, totally waterproof - been functioning on Elyse now for 17 years without any problems.