Willy, I dont care for HB products and have heard similiar stories like above from several of my fishing buddies. Look into the Lowrance Elite series. Got a buddy with one and he loves it. Im hoping to order mine soon.
Also look at the back track feature on them on youtube. It allows you to actually scan back over the bottom structure you have already passed and mark the spot via GPS way point. Pretty sweet for finding new spots.
Watch this:
http://www.youtube.com/watch?v=6eiuWKvVDlo
Cabelas had them on sale for 399 last week.