I have a 997 on one boat and a HDS8 on another, and I like the HDS 8 best, probably. I have two connected by Ethernet cable and I like the way they share data and that I can view SI on both units. The GPS will track at speeds below .6 mph. The 997 is more user friendly, and probably more durable. HB customer service is great---read a lot of horror stories about Lowrance CS, but I've not experienced it.