If you are expecting to spot each salmon that swims under your boat, I think you’ll be disappointed.
I find that salmon don’t mark very well even with “high end” transducers and sonar. They don’t have much of a swim bladder, so the returns from salmon are pretty weak unless they are right in the “cone” and your sonar is tuned just right.
In comparison, rockfish and baitfish light up like roman candles and are very easy to identify. I think a lot of times when people say they “marked lots of fish”, they most likely saw something else - debris in water, weeds, etc.
Lots of times I’ll hook fish without having a definitive mark on my screen beforehand (that’s running a 1KW B175HW transducer, with the gain turned up as far as I can go before the clutter gets too loud). Sometimes it happens where you’ll see a salmon swim up and bite the gear which is cool, but I don’t expect to see that every time.
I’m most interested in the following info from my sounder in decreasing importance:
1) depth (if fishing structure as charts aren’t always 100% accurate)
2) depth of bait
3) depth of salmon. They don’t mark well, but after a while you learn what to look for and can see them if you get a good return.
FWIW, I don’t find it particularly useful to see my gear on the screen, that’s what the counter on the downrigger is for.