I used PHPCR-ODM with Jackalope / Doctrine-DBAL implementation so far on my Symfony2 website. However, now I'm considering using MongoDB instead of the mentioned one as a content repository, hopefully with PHPCR-ODM layer.
How much does it take to replace these DB "engines"? What am I supposed to take into account when doing this? What are the requirements from me? Any suggestions and recommendations are welcomed.