João:

Don't worry - there is lots of interesting stuff here on APUG, so you should have no trouble getting enough posts to be able to post links.

For lenses like yours, sample variation may be more important than model differences. I would suggest you try a few prints at your favourite print sizes. If you are getting sharp grain at the centres and corners, you will most likely not benefit from an "upgrade" unless the small maximum aperture starts to be an important inconvenience.

If you are looking to larger enlargements (16 x 20 and larger) the APO enlarging lenses definitely make a difference.