For color tags I’m using Capture One and Graphic Converter and Lyn and Finder… I don’t say, my color tags do aways do the same classification - since I saw Photoshop overwriting and “forgetting” color tags in Bridge (and on Windows ) after I saved a tagged image, I handle them more or less like a couple of post-its and just for a temporary sorting job. Interestingly only RAW converters are too stupid or too arrogant to “understand” color tags within Mac OS - all three browsers show the color tags. And with the two colors (three, if I count “no color” as a color) I get nowhere.
You didn’t ask for extraneous opinions but for me I think part of the value of color tags is the filtering ability. I used color tags heavily in capture One pro and it was so easy to filter based on that and any other number of parameters. I could easily filter on the purple images shot with the 70-200. Or the yellow images shot with the 200/2.0 and also based on keywords. It was great for large projects like the multiple nutcracker stage performances during show week.
4 - For color tags, which of the following software do you rely on?
I use IMatch for managing and tagging my photos. That’s also where I assign color tags.