Shoot a series of colour AND b&w films, with several different frames of closest focus, the medium distances that are your average rangefinder setting and at infinity.
Then sit down with prints from each, 8"x10" should be ideal quality and, if you can afford to, 11"x14" or 20"x30" prints of the two best images.
Look at the details, grains, colour depth and rendering and see if they please you.
If so, use the lens and let it make the best images it is capable of.
If no, keep looking for your keeper 28, but also keep in mind, some lenses render their best work in either colour or b&w, and give cool and warm images differently, so you may end up with two lenses, or more.
Godspeed