I agree with Saenger - a Block Party is an event which has to reach the same criteria as a Mega, and should be treated the same way. Take London Calling for example (GCAK7KC). This is a bi-annual Mega, and would have been a Mega again this year if the opportunity to become a BP hadn't arisen. People attending London Calling would consider this a Mega, and expect their stats to be increased accordingly.
IMO BPs should be treated the same way as CCEs, i.e. counting toward statistics as well as providing the extra add-on.