The 4520 is a direct replacement for the 452 so you should just be able to swap them.
The firmware has been fairly stable for a number of years now, most changes have been fixing edge case bugs or minor changes to deal with the way people use the controller so generally if it works I wouldn't bother changing it.
(My main indexer still has V1.2 in it! I do keep meaning to swap it but there's never been a need.)