I have a Cabellas portable Eagle 480 setup that I'm still learning about. Any basic B&W depthfinder should help mark depth and contours while showing arches for fish.
Trout, I would think, would be easier to read due to their size. Sometimes when I'm out looking for bass it can get confusing if the marks are rough and you don't know if they are weeds, or clumps of bait fish. I haven't used it in the deeper trout waters but it should do a decent job.
Best Always,
Vinny
PS: Color would be nice but costs more.