Multicatalog is an outstandig flexible Catalog Plugin which can be very easily extended and has a clever TypoScript-Structure which let's you intuitively modify and extend the output.
Currently it's based on oldstyle pibase, but now extbase refactoring was kicked off.
Easy Extensibility is a key feature of Multicatalog and the main reason why it was not based on Extbase yet. Unfortunatelly extending Extbase Model Classes is not much fun, while extending this catalog is a matter of just adding a field to the database or dropping a line of TypoScript.
But I decided that Multicatalog can merge the advantages of its current implementation with those of the MVC framework.
Starting with 0.6.0 you can experimentally switch to the Extbase version of the catalog by checking a box in the EM - but this won't work yet in Frontend.
The goal for 0.7.0 is to have Multicatalog completely based on Extbase, with one exception. I'll implement my own Model Classes for this Extension, so that the easy Extensibility lives on.
Having Fluid as Templating Engine improves the flexibility of this extension even more. With the already very powerful TypoScript Configuration Options of multicatalog and the possibilities of Fluid the Admin has two powerful Tools to fit the catalog to his needs.