I am looking for a new sonar unit and need advice. Is the only benefit to color the fact that you can see it better in the bright sun? Comparing the Lowrance products: Is there an advantage to 480 x 480 pixels over 320 x 320 pixels for crappie fishing? Also, is there any advantage to 4000 watts in the X135 over the 2400 watts in the X125? Thanks.