How quickly would I be able to toss silverstrip + blogs + workflow and get a 4-stage approval workflow before a blog (or its comments) get "published":

blogger -> Manager approval -> Compliance approval -> VP approval = "published"

Corporate Blog, with legal repercussions state-by-state for "misstatements"...

Assume I know nothing about Silverstripe, minimal framework experience (Drupal custom modules, WordPress module), and a decade of custom PHP development.

How modular, well-documented, extensible is the Workflow module?

Has anybody ever tried to customize it to add weird "role" rules or anything like this?

I could code a working prototype in a couple days, but wouldn't have RSS, pingbacks, 3rd party integration, WYSIWYG editor etc...