I had the same question about the ticket limits prior to the general onsale and emailed Ticketmaster. I did get four tickets during the presale. Here was their response:
"Thanks for contacting us, my name is Leslie, I'd be happy to assist you in any way possible. I'm sorry about any confusion regarding the ticket limits for this event, 6 is the total ticket limit for the presale and general onsale. You can purchase 2 more tickets without violating ticket policy."
So....I was only able to get 2 more at the general onsale. Their ticket limit descriptions are very confusing. Hope this helps.