I'm not quite sold on Diagon being the great crowd killer most think. Maybe once Hell Week rolls around but really have you've seen the rides have long waits? Nah because people are doing the houses, hanging in zones or drinking. With as high as prices for this event are. You think people will spend 1-3hrs in Diagon. With all that said I'm just glad it's finally announced and over with.
There was a night last year during the 1st week of October where Mummy was 75 minutes and MIB was 45 mins all night. We needed Diagon and Gringotts BAD.