OK got a couple questions. I have no experience with any garmin products but kind of like the looks of the 73 SV. I'm wondering though how does it compare to a Helix 7 or lowrance Elite/hook 7. I don't know much about wattage or 800Khz transducers or anything like that, but the price point with one loaded up with maps is relatively close. Is the SI and DI as good or better than the other brands? What about linking units together? Is it just a cable or do I need special boxes and what not.