Coming from the Gentoo world I am really frustrated by how user-unfriendly rpmconf is in comparison to the fantastic dispatch-conf.

One very simple change that would make this tool a lot nicer to use would be the use of colored diff outputs (/usr/bin/diff --color=auto). I had a brief look at the code and it seems like you are using python's built-in difflib, which doesn't support this. So the fix would most likely be making rpmconf always use an external tool, and then let the user configure which one.