I spent some time reading through your post and had some notes/questions to consider. I don't nessicarily need the answers to these, but they are things that should definitely be considered/answered in your planning if you're moving forward with it as a project.

• Verification
  • So registration does happen? You're just not using your keys, and making an account on the site? I don't quite understand how or what you've be verifying.
• Posting a Bounty
  • Where are these stored? Are they posted on the blockchain?
  • How are notifications handled, email? Is so, are you planning on maintaining a database of email addresses?
  • Do bounties have tags or some form of categorization?
• Participation
  • How exactly is participation tracked, and in what ways?
• Escrows
  • I'm not sure how you'd plan to escrow funds without actually assigning the task to someone in the beginning. You need a recipient in order to start an escrow transaction.
  • You could probably use escrow as the last step (delivery), but that doesn't actually prove a bounty is funded until the end.
• Updates and progress
  • Same with bounties, where are these stored? As users update their progress and upload files, are these all stored in this system and not the blockchain?