Can anyone point me at the documentation that details the functional differences between a PFC3A (on a SUP720) and a PFC3B?
The current docs (http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/product_data_sheet09186a0080159856.html) detail the difference between a PFC3B and a PFC3BXL, but not the PFC3A.
The big difference between PFC3A and the other one is:
1-ACE counters (This was actualy a bug in PFC3A, turned it into a feature)
2-MPLS in hardware
In order to compare the features/performances of the first PFC3A ( in the EOL/EOS WS-SUP720) with the later generations (not listed in the different tables provided in the link), you can take the information from the pdf in attachments.