The opposite situations pertains here, I'm fairly sure I don't have any MUI programs installed at all except Scout.
So, mmh, tell us which Reaction applications you use, exactly.
Let's assume you use AmigaOS for daily stuff. Is there a Reaction mailer? A Reaction PDF viewer? A Reaction audio/video player ? A Reaction IRC/MSN/Whater client ? A Reaction filemanager ? Are there even Reaction replacements for the quite simple preferences programs of OS3.x?
The only serious Reaction (well Classact) applications I know is AWeb, and Codebench under OS4. The rest is rather simplistic tools.