I have used TF4 and 5 on lith prints. Never really noticed that one bleached the highlights more or less than the other. As far as I know, it is a fact of life that fixer bleaches highlights. After several years lith printing I am still impressed at how a print lightens in the fixer under the safelight. So I just try to factor that into my exposure time to end up with the highlight level I want. For me, if I can just barely see a little color in the lightest portion of the fixed print, the dry down will give me just enough more.