I can't really answer this, but I do have experience of the older 18-50 f2.8 on APS-C, and on that format, it's a really decent lens. The newer one is supposed to be improved, so optically, it should be a decent upgrade to your existing lens. However, it doesn't give a very wide angle of view on 4/3, so you would probably be changing lenses more than with the 14-54 if nothing else, particularly if you frequently use the area between 14mm and 25mm - that inconvenience alone might make the Zuiko the better choice.