I need a new sonar/chart plotter combo for the front of my boat, Trolling Motor mounted transducer. Will I appreciate the Lowrance Elite 5 with the chirp technology $250 more than the Elite 5 HDI without Chirp? Cabelas has both with free shipping now but BPS does not have the Chirp units. BPS say they will have them at my BPS (80 miles away) by the end of the year for $100 off. ???? that. Advise please.