My two cents,
based on what i read or before I bought a set of ap1s.
How often do you play?
If your a occasional player, maybe you may get more satisfaction out of the ap1s as its still more of a game improvement iron and to me its quite if not very forgiving. I feel if I do not play often then I may not always hit the ball at the sweet spot. Not to mention, its relatively cheaper then the ap2s too.
Maybe you can share about they u want to change your G15 irons? To me, I guess they are pretty much the same.
Hope this helps.