I just purchased my 3rd HDS Unit. This is becuase of boat changes. I just sold my Bayliner 2452 that I had installed a HDS 5M and a HDS 5X. I am very happy to go back down to a Lund 17.5 ft. A better boat to fish out of, in my opinion of course. I just installed the HDS 5 Gen 2. All I have had are the 5 " screens and they have been fine for me. If you are going to use structure scan, you should purchase the 7-10" units. Otherwise, I do not see an issue with the 5 " screen but larger screens are nice to have if you want too spend that much money. The HDS 5 units are easy to find fish with and I do not need to keep my face stuck on the unit. As far as reliability; I have never had a single issue as they have all worked great. I use a little comon sense and make sure that they are not abused by keeping them always stored indoors and not subjected to constant heat, sun, rain or freezing. I would by one agian.