I saw the same classified ad online and almost pulled the trigger.
I have a HDS gen 2, HDS gen 1, and a HDI 5 all networked together. the HDI 5 did not have ethernet or NMEA 2000 so I have it connected with a NMEA0183.
I’ve been slow to get rid of the HDI5 because of the three, it is the only one that will take my MN Lakemaster chip.