Yes, you can choose in-person service and go directly to Buffalo office. Try to be there before 7:45am since it lines up quickly after 8/8:30am. I was 3rd in the que for the receptionist to receive all my documents (PPR email, RPRF, Photo & Passports). Arrange them beforehand. I took a seat and waited 3 hours. I was given a token when I submitted my docs and they called everyone by the token#. Anyway, I was called at 11am and handed over my passport with Visa and CoPR by the same receptionist. I was briefed how I should land on the border while going back to Canada.
This is straight copied from my PPR email:
"Passports may be brought in on Tuesday or Thursday between the hours of 8:00 am and 11:00 am. Bring this email when you come. Every effort will be made to have your passports available to be picked up between 1:30 and 3:00 pm the same day."
Hope it helps. Good luck!