tubesforever, please let us know the result! If you roll tubes you have rather big changes, which stays recognizable even if you digitize the result (tried by myself). I doubt that you will have such result just changing the fuse, even if the fuse will be solid gold. If I wrong - you can try it yourself, supposing you have decent computer to record the changes. Maybe it is possible to upload small portions of most recognizable differences somewhere to prove you words.
But I'm repeating - the changes (if any) are more from the liking of the good and not cheap things, not from the real impact on sound.