A fishfinder is like a boat. The next size up always looks better. I wouldn't buy anything without trying to see what it looks like in actual use. That 5" screen is going to be pretty hard to read in the bright sun. Personally, a 7" screen would be the rock bottom smallest and bigger would be better.
2015 Seaark 1872 MV CC Etec-90
Two Helix 12 CHIRP SI's, , MinnKota Riptide ST80/i-pilot Link, Bob's Hydraulic
Bitter Gun Owner