I think it would be useful if CompareIt! complained about not finding the username.ini file passed via te /i= parameter. Especially because it's not very clear where CompareIt! will look for this file if it doesn't include a path (in the current directory? in the executable's directory? etc.)
Right now CompareIt! silently ignores a non-existent username.ini file and uses the settings in its ini file (or some default settings?)
Hope that helps,
Dan