[Zope] Experiences with big ZODB?

I tested ZODB with a size of 2GB with a own python product for zope. My experience is that it can be used for applications if you design your product right (Using BTrees) and if you have a python with support for large files. Are there any problems I might experience with such a big ZODB (about 8GB)? I have to decide whether to use ZODB or a relational database. I would prefere ZODB. Any comments? thomas