I'm surprised that Tobeck didn't tell you to insure your boat with him!!!
(Actually, I did and saved money doing it!
)
I would take a look at the HDS 8 as well. When you consider the time you spend looking at the screen, bigger is definitely better and increased visibility of your sounder from the back of the boat is a HUGE advantage!
Speaking of the back of the boat, have you considered slapping your old sounder on a RAM Mount and putting it by your kicker?