Re: choosing between humminbird 597 ci hd di or lowrance hds5 structure scan
If your fishing is geared toward finding good structure (that fish will be near) than DI, SI, or structure scan will help a great deal.
2D is better at locating fish, especially in the water column. DI/SI/SS can provide tighter details that could help identify.
The 597, will do 2D and DI. To compare to an Lowrance structure scan, you would want to look at a 798.
I have had a 798 for a number of years. SI will allow you to scan a large swath looking for structure. If scanning for large stucture, can do 150' to each side. I generally only scan 70' to a side, looking for smaller items. My primary fishing grounds are mostly rivers, which do not have depth maps, let alone structure maps. Spring high water and floods are constantly changing the structure.