I have the humminbird piranha max and a lowrance x-4 pro on the same boat, they both do exactly what I need to know, the depth, The piranha has a better looking display
than the x-4 but the x-4 reads in inches rather than just feet. That way you know when you are going shallower or deeper by the depth reading, if you are in 4 foot of water
with the piranha it will only read 3 foot if going shallow or 5 feet going deeper. The x-4 will read 4.6 feet then 4.8 as you go into deeper water and that is important to me.
Another thing that is important to me is that the x-4 will read in much shallower water than the piranha, the x-4 will read shallow water down to about 1.5 feet with no problem
the piranha starts blinking in water less than about 3 feet. I use these on my shallow water boat, normally from two to five feet of water. Both units cost about the same
and both works well for what they are.