My pops is needing a new fishfinder as his is on the fritz. I was hoping to surprise him with a new GPS/fishfinder combo for Christmas. He fishes mainly coastal/inland areas and Sabine Lake. Cannot do deep sea/rough water in his boat. I have a friend who has a Garmin 541s and has a lot of pre-loaded information on his SD card that he would program into the gift beforehand if he gets a Garmin. They discontinued the 541s model but I have been looking at the Garmin Echomap 50s and 70dv. Does anyone have an opinion on these models/any of this? He fishes salt 90% of the time but will occasionally fish east texas freshwater lakes. Thanks.