I've been pointing this out everywhere but double XP does NOT equal leveling twice as fast. The work it takes to get from 1-7 will get you to 10 this weekend.
In fact, the ONLY people who will level twice as fast (based on the numbers) are people between 40 and 50.
My 32 will get to 40, working as hard as it normally takes to get to 36.
The trick is that because required XP goes up, higher levels get a bigger break than lower levels. And between 40 and 50, XP needed to level caps off. Meaning that the XP from 40 to 41, when doubled, will get you to 42.
But you won't see newbies getting level 20s out of this unless they put the work it normally takes to hit 16 or so.
I plan to use this with my 32 to avoid the late 30s grind and shoot for level 40. If I get the chance, I'll try to marathon play tomorrow and go up a level or two before so that I can take better advantage of the event.
The higher your level, the bigger the advantage this event gives you.