Quote Originally Posted by cray View Post
Newley according to Humminbird Greg it's same as 798 less one card slot and a couple of preset buttons.
Another difference is that the 598ci HD Si unit cannot be linked to another unit. If you saved a bit more and instead purchased the 798ci HD Si model unit, you could also buy an adapter cable (AS-EQ-QDE) and an Ethernet Connection cable and be able to share lots of information between the units.