The HDS 5 with 83/200 for shallow water ie lakes and rivers. In site is a much better mapping program that shows contours with depth. It also has the capability to have down scan and side scan with the addition of Lss-1 or Lss-2 and the transducer to go with.
5x has no GPS I think it can be run with a unit that has Lss hooked to it in a network but basically high priced depth only finder.
HDS-5 would be nice if you wanted to expand later with the Lss functions or just as sonar and GPS. I don't have one yet but am convinced if your going to buy one get the GPS for marking brush,stumps and cover. Plus with the in site let's you follow breaks and channels.
Hope this helps some.
Proud Member of Team Geezer
Charlie Weaver USN/ENC 1965-1979