Having worked extensively with PHP for a number of years, we have often managed and customized well-known open-source systems, from generic website builders like CodeIgniter to publishing frameworks like OJS or complex learning systems like Moodle. We share the object-oriented programming style from most of them, and are glad extending them with useful features that give them a specific added value. VuFind is a very useful tool in its area, and extending its ability to communicate with external library systems will surely contribute to enlarge its operational field. The ILS Driver Specification is technically very clear and should pose no particular problems to be implemented. Its main strategy of keeping most of the logic inside the driver is not only advantageous for the system, which can then call it in a more transparent way, but also for the driver itself, that can be then more self-contained and use its own coding rules. All in all, the task you propose is interesting, and worth the effort of getting it done in two weeks. We will be able to confirm that once we know the concrete modifications that are to be done.
Regards
The Bramfeld Team