OK , I have a Garmin 240 at the console of my bass boat, want to install one at the bow . But when comparing the 240 to the 250 I find the 250 has more features than the 240 for very little money more , which begs the question , why does Garmin maintain the 240 in the line ? Does it have some operating feature which endears it to owners over the 250 ? And the 250 says transducer suitable for trolling motor or transom . Some vendors say 240 transom only , but a couple now list the 240 as the standard supplied transducer as being dual purpose ?