I have the HDS-7 unit and wish I had purchased the HDS-8 for the larger screen. Take this into consideration, how big of a screen you want/need (and can afford of course), when you make your purchase. I now regret not getting the larger one up front. I also have the Navionics Hot Maps for Candada. Unfortunately, the lakes and rivers I fish ... are not yet HD. My current card is several years old and, unless the newer versions give me soemthing I don't already have, I'll keep using what I got.