http://ww3.brighton-hove.gov.uk/index.cfm?request=c1204374&action=showDetail&application_number=2017%2F03379%2FLAPRMV
Yep, the capacity isn't increasing, as stated as above. But they could have more seats than capacity and therefore achieve a full capacity crowd, despite segregation.
Seats...
I see tickets are on sale to Man City fans now and they have numerous points categories.
https://www.mancity.com/news/tickets-and-travel/tickets-and-travel/2017/july/brighton-v-man-city-premier-league-tickets Good to see they have similar binfests to us...
To be fair, if there wasn't a lot of difference there would be no point in doing tiered pricing. You're supposed to think "well of course I'm going to the Man City game, but that West Brom game looks a bargain so I'll go to that too"... But then I don't agree with tiered pricing at all.