The main reason for this change was to ensure that new users would always log on to a server, even if the nicknames they had chosen were in use, since new users would probably be confused by the "/nick" appearing in the editbox.

I am going to change my approach to this - I will remove the automatic numbering feature and will instead pop up a dialog telling the user that their chosen nicknames are in use and asking them to enter a new nickname. The dialog will have an "Always show this message" option, so you will be able to turn it off. If the dialog is disabled, mIRC will display "/nick" in the editbox as usual.