I've had/used Eagle depthfinders for years. Currently have :
Eagle ID Fishfinder
Eagle Z-5000
Eagle Magna II
(all three of which are no longer usable)
I also have a Lowrance Flasher unit (currently being used on my fishing partners boat).
I don't remember giving more than $150 for any of these units, and more like around $100 for most of them. They have all performed very well, for the purpose I purchased them for ... finding the water depth, and showing bottom contour and cover. I almost always (99.5% of the time) run them in auto mode. This is mainly due to the fact that I don't often fish directly under the boat ... I'm usually casting to cover, away from the boat. But, I do occasionally run across cover, that I didn't know was there, and have found new spots to fish by doing so.
IF/when I purchase a boat, for myself, I would not be hesitant to purchase a Eagle brand, or Lowrance brand, depthfinder for it. Proper placement of the transducer(s), correct angle adjustment to transducer, and placement of the unit itself ... can make even a low $$ depthfinder, a seriously effective tool for locating the structure & cover that fish like to utilize.
Understanding the limits of the unit you're using, the cone angle (and what it can/can't/does show you), and the interpretation of the "picture" being shown on the screen ... takes a little studying, and use time. Study the manual, or tutorials, and don't "expect" the unit to find the fish for you, and you're good to go. Remember ... the unit can only show you what it "sees" within the confines of the cone. And a 20deg cone angle will only show a circular section of the bottom, that's 1/3 as wide as the depth of water you're in (and that's at the widest portion of the cones influence ... ie, the bottom of the cone --- it's showing proportionally less of the water column, the shallower/farther up the water column, towards the transducer, that it's looking at)
When used in conjunction with a good topographical map, most any depthfinder can help put you closer to where the fish should be. But, you've got to understand the fish, its habits and habitat, in order to know where the most likely place to look for them, is .... THEN use the depthfinder to find the depth or cover that they're most likely on/in/around. Where they are, how deep they are, what they're around, and the conditions under which you're fishing ... should dictate what methods & presentations (& even baits) that you are most likely to have success using.
.... luck2ya ... cp :cool: