As an option, perhaps. For me, syntax highlighting works best when fairly restrained (else "angry fruit salad" ). I think FM got it just about right (for a first pass, at least). That said, I wouldn't mind having the ability to color variable names wherever they're cited (as opposed to the Set Variable step itself), much as field names are currently colored, but that's about the only addition that I'd really want at this point.
You may wish to check out the MonkeyBreadSoftware plugin, which, on the Mac at least, adds more syntax coloring than the FM defaults, and has been updated to work with the new Script Workspace.