Hi msrdyI am worried because, it has been more than 6 months in my case. Moreover, clearing eligibility is most important step in the PPR process.
I would not recommend you withdrawing the application, as i believe that this means you will need to be issued another invitation to apply. If i remember right it states when they issued the invitation that if we choose not to apply at this time and exceed the give time frame(90 days) we will need to be issued with a new invitation to apply and that there is no guarantee that another will be issued just because you were already given one invitation.
There are lots of cases where is exceeded the given time frame, I would suggest that you wait a few more weeks and see how it goes. However do keep following up once in a while and see how things are progressing, if you know your Local Visa office(LVO) maybe contact them directly and see what's the hold up as you have exceeded the standard processing time (if you have).
Also you can open a case specific enquiry if you have exceeded the 6months mark from the AOR date.
Hope this helps and wish you a speedy PPR.