I guess I’m on the other end of the spectrum, pending what my expectations are. For simple use to identify fish or look at the general structure, B/W is fine and will suit the needs. Also in lowest light periods that are still viewable, all cameras will be in B/W mode to get some form of image.
If your trying to identify very specific details about a location or structure, color will have some distinct advantages.
Grayscale on a typical image will have about 7-9 shades ranging from pure white to pure black. In contrast to that, the human eye can recognize nearly 10 million different shades of color. Now, viewing a color underwater image isn’t going to produce the vivid colorful images like the best quality HD TV shows, however, it does show a greater range of both hue and saturation. This makes it easier on the eyes for long term viewing and detecting tiny distinctions.
Myself, (admitting I am a little analytical) I look for much more about a spot than just if fish are cruising by or how they come in and look at a bait. I use my LX-9 for both ice and open water. I want to see more specifically what type of aquatic life is lurking around. I’ll often intentionally hit the bottom with the camera then lift up to see what floats up. You would be amazed at what you see for larvae and other little creatures.
Now, like all situations, conditions must be conducive to giving appropriate results. I was the Milwaukee Harbor (McKinley) for a day. There, I use the camera to simply see how high in the column fish are cruising. B/W is fine for looking at a fish swimming by. Milwaukee Harbor Browns The water was a bit “milky” looking because of the 20 mph north winds the day prior and the lake was stirred up.
Here is a sample of how I use it in open water to compare spots. This a rock hump that on the sonar looks great…but fish don’t relate to it all summer. After a closer look from this Aug vid, I understand why. Deep water rock hump video
So it all comes down to your expectation and value. If you don’t need to see the fine details, you won’t see value in color. If you want to get the most out of your equipment, color will give you an enhancement and value for your investment.