If you're usually in the large chainring and 21,22, or 23 in back, you're probably in the wrong gear most of the time - - and in 53/23 you'll probably be wearing the chain.
If you're finding that when using the 53/12, you need to go further down, then you could get an 11-25.
If you're having trouble on hills even when in the 39/25, you could get a 27-12.
If you never ever ever use the 39/25 (viz. if you never ride on notable hills), and would fancy being able to fine-tune things to get just the right gear a little bit better, you could get a 23-12.