It should have no affect...The only thing u will see..perhaps..when trying to open your game with 4.5 is a message saying that...
This was created with another version of AM..opening it might destroy work...Save before u proceed..--something to this affect..
So in essence..save a copy of the game folder...You should always have the most updated version...of AM..
That being said; I have opened it..proceeded after that message...and nothing happen at all..and have done that with each version....You just have to copy over plugins again..But to be safe..make a copy of your latest game..
All games should remain in tact...I've deleted older versions before..Although u don't have to do that..U can simply open up your games with the newer one..--This has been my experience...perhaps someone else has a different answer..