Hi, I am currently looking at getting a new sounder and had decided to go with Furuno FCV600L over Raymarine. But now I am wondering for an extra $350-$400 dollars would I be better off with the FCV620 or would the 600L be just as good.To date I have only had cheaper sounders so I am a bit inexperienced in the world of sounders. I mainly fish around Hervey Bay but intend to go outside a bit in the future.