The HD designation on the 798 only indicates whether it has an Ethernet connection or not ..... All the 798 units had the brighter LED backlight.....I doubt very seriously if Humminbird can update it since the unit hardware connections are completely different on the HD model....since it has Ethernet.
On the 898 and 998, the HD designation does indicate whether or not it has the brighter LED backlit display.
_______________________________________
Looking for the one that makes it all worthwhile.