Lots of people, including me, are speculating why NDVO is not sending the PPR. Since there are hardly handful cases to deduce any pattern all of this seems like a random process. From what Diplomatru had posted a while ago, the local VO, after your meds is done, outsources the security checks through a third party (was it called IPA?) ... I am sure that the results obtained from this agency would take differing time for different cases depending on number of dependents, number of countries visited over the past 10 years (outside US would require more time to complete the check, possibly the most time taken for security checks for people who have visited and worked in middle eastern countries...just guessing).
As long as there is no "directive" given to NDVO to clear backlogs, I think that we will never see a "flood" or "rain" of PPR we all expect. Instead we will see a few cases intermittently get PPR from NDVO.
I hope I am really wrong !!!!
Cheers!