Couple things to consider imo when looking for a new finder on a smaller boat. I'm guessing with a 16ft boat in your sig that full-blown auto-pilot isn't something your looking for correct? Do you have an electric trolling motor? Brand? I ask because both Lowrance and Humminbird are more compatible with a specific brand trolling motor (HB/Minn Kota and Lowrance/Motorguide) Lot of ppl will use bow mounted TM as autopilot of sorts on a smaller boat. Do you need/want down/side imagining? SI/DI is about the cost of going to the next screen size up so really consider if it is something you really want.
Personally I have an 18ft boat, Minn Kota Terrova with iPilot Link connected to a HB Helix 9 and love it. I also have a Helix 7 SI/DI and almost never use the SI/DI, for the same price I wish I got another non-imaging Helix 9.