IF you plan to keep the boat long term and you have the spare cash just possibly, if not stay with the 550s, afterall you are going to be glancing at it whilst travelling at 25 knots. All you need to know is am I going in the right direction and will I hit anything in the next 30 seconds until I glance again.
Sounder add on worth having, helps see just how shallow it is which helps avoiding parking your rib on a sand bank.
Nice feature is the built in ariel so one less cable and mounting to worry about.
Have one on the yacht with Easy AIS, but you don't need that because ribs have to give way to everything that floats.
Nice bit of kit.
Ribnet is best viewed on a computer of some sort