Thanks for all the feedback. A lot to ponder. Makes me think I need to take the Lowrance HDI 5 I have at transom and put up front and then buy SI for transom.
"D" LIKED above post
Would work fine . Is Exactly what I had before I up graded to a Helix -7 . Mainly for maps for pulling cranks . The processor was a little slow on the HDI unit, but a dang good unit for the money .