Hmmm taking data off an mmo isn't too smart, Yes girls generally do kick more arse as a general statistic at them, because we play them more to chat away inssessently...
HOWEVER, the most hardcore of the hardcore skill wise both in PvP and PvE, and I'm talking the elite of the elite, 30 people in the world kind of thing, are generally male in most Mass multiplayer games.
I'm not being sexist fellow bra wearing-ladies, it's just true. WoW's top guild has about 3 girls in it as far as I am aware. The PvP teams? Hah I have rarely seen a pair of boobs sitting in one of those live competitions.
I do believe we probably invest more time... yes, but that to me isn't hardcore...
Hardcore is somthing alot more, Gamer's instincts in full prime, Knowledge about what you're supposed to do subconciously ready at any second, Multi-tasking at its best, and boundless dedication to whatever it is you might be doing.
That, to me is hardcore, not how long you're playing it.
Some of the so called MMO-hardcore guilds/teams spend less time playing each week than your average joe... No really.