Both use base and modifying @ISA provide genuine inheritence. use base is a newer approach which is a bit cleaner syntactically, but has the same effect as using the module, then putting its name into @ISA.

Using Exporter amounts to using mixins. This means that the methods don't care what class structure you have so long as the object used to invoke the method responds appropriately.

Using inheritence is a more generally accepted practice. But Exporting object oriented methods can make good sense too. Ask yourself this: is there a hierarchy of inheritence which makes sense for the app, or are the helper methods more unstructured. If the former inherit, otherwise stick with your Exporter mixins.

Phil