Greenberg, I agree with your understanding
I think, the key is where does the I-140 go after it has been approved, who keeps it and who needs it?
I think if I-140 says that it is for CP, it is sent to NVC, otherwise INS retains it.
In our cases NVC would then send the packet 3 to the attorney or you.
Now, if you apply for I-485, and DO NOT SEND the packet 3 back to NVC, then NVC would issue the notice in about 10 months inquiring the status to your attorney or you. NVC cannot get immigrant visa number from visa office until they find the complete packet 3. ONLY AFTER they find the packet 3 complete and get Immigrant visa numbers, they send the papers to Consular Post in the foriegn country.
In meantime, INS would continue with I485 application. When INS assigns the case to an officer, and if I140 is required, then they can retrieve it from NVC.(This process does not take long, max 2 weeks).
The problem is worse when it is other way around. Meaning, if you choose AOS at the time of I-140 filing, and later file I-824 to change to CP. In this case, the INS would have kept the I-140. The I824 application is a trigger to INS to send the I-140 to NVC and initiate CP. The INS is slow in this process and at some site have read delays of almost 1 year.
So, I think, people who filed AOS instead of continuing with CP needs to wait and do not worry, It is the people who planned to do AOS but changed to CP need to worry about the delay..
These are just my understanding and I\'m not an authority on the subject, Please use your discretion.