Actually, database-backed role definitions have been requested a few times
already. In my experience, the DSL form of defining roles is sufficient for
many projects. I would be glad, though, to add the database backend as a
second option and would accept patches.
One of the interesting parts of implementing the database backend is to
provide a usable administration, in particular concerning the definition of
complex rules.
This ticket might be a good starting point:
http://stffn.lighthouseapp.com/projects/20733/tickets/11-refactor-engine-and-
reader-to-simplify-adding-further-reader-backends
Steffen