Re: standard horizon depthsounder
Fish finder technology has moved forward leaps and bounds in the last 2-3 years. Just about any of the new units would be an improvment over what your currently running.
Transducer wise, as long as you stick with Garmin, Raymarine, Furuno, Sitex etc, chances are pretty good that you can reuse the exisiting transducer using an adapter cable or a splice box.