I am currently writing a CMS and remember someone (it might have been on here) criticise the existing CMS for not having a robust enough user permissions system. I\'ve got a me
I wouldn't necessarily dismiss the fine grained control system you have now. If you have one that is adaptable focus on hiding away the complexity by providing a simplified interface (eg use the facade pattern or the adapter pattern). The benefits are that you provide users with the simplified version (simple permissions like 'admin' can 'delete' a 'post') while still retaining the fine grained features should you need them later (eg more complicated permission handling is to allow to delete posts when the post is your own post in category X). Then you can provide an alternative to the simplified version for that need in some places.