I have dual 3010's on my 45' sloop, one up at the helm and one down at the nav station. With the GMS port expander there isn't anything it can't do. There is even a remote available for it,(can't imagine why). With 2 plotters one will automatically go into slave mode. The touch screens have issues being in direct sunlight down here in Florida. I have been using the 3010's since 05' and have about 10,000 miles on them without a problem. The XM weather works as far as St Thomas and with the up graded Gsd 22 the sonar works better. I don't know what you will get for spending the extra money on a 4 series system. Good luck in your choice.