The problems with this approach (if i understand correctly)
1. You still have to send bitcoins to this "M of N" address and so you still have to wait while this transaction get 6 confirmations.
2. What is incentive for the trusted auditors? You could send fees as an output in transaction, and if they see that tx includes fee they provide a signature, but tx would be huge, compared to standard tx
3. What to do in case of auditor closing its service, well, there is small chance that all auditors shutdown their services at once, but if you send bitcoins to this address and then want to use it after 2 years you may, to your surprise,  find that these auditors don't exists anymore.

However this is still much better than trusting to the one green address provider.