For myself I think I would agree that grappling should be enough if the woman is FULL-ON attacking. I suppose the one exception might be after a kick to the nuts. I don't even think thats fair in a male on male fight and you couldn't really blame a guy for lashing out after that.
This is a really delicate issue but I'll try my best to contribute with a personal story. A while back I lived with a group of people in a house including a couple. They were the type that were REALLY passionate. Either shagging all the time or shouting down the house. The girl in the relationship wanted out but she didn't want to be to the dumper, she wanted to look like the good guy. Her plan was simple, she was going to goad the guy into breaking up with her or giving her a slap so she'd have an excuse (her words! They're still both my friends). She started by pushing his buttons early on in the evening, that didn't work, EVERYONE knew she was acting weird. She then went further, starting a full blown argument and saying how much she hated him (even though she didn't, she just wanted to go forth on her own). That didn't work, though the guy was HUGE, he was the nicest, calmest guy in a situation I've seen and wasn't taking the bait. She then tried to goad him further, bringing up stuff that she'd done when they'd been on past breaks, still didn't work. He was mad, sure but he was generally a sane guy. Knowing she wasn't gonna get anywhere after a good hour or so she made the situation nuclear. Lately she'd been working late at her job at strange hours and one of the guys at her work had a MAJOR creepy crush on her and kept leaving stalkerish messages on the phone. She said that indeed, she'd been staying late after work to shag him and had even been with him that day. This was all false but she shouted detail after gruesome detail into the guy's face, and I mean really nasty stuff. He snapped. Threw a punch into her face followed by a couple of jabs with the left. The moment after this he collapsed on the floor in a huddle of tears before going straight to the phone and calling the police on himself. He didn't know he'd broken her jaw with the first hit but he didn't care, he'd done wrong in his eyes and promptly asked to be arrested. Everyone else there was conflicted. We were mixed between girls and men and none of us could figure out who was to be blame. Afterwards the girl even said she was stupid for what she'd done (rather odd as she needed surgery to fix her jaw!) but I'm still conflicted as what I would have done in that situation or who was "wrong".
Sorry for the speech but thought it was food for thought beyond the "if they hit first" stuff, into more dark territory. Sorry if it bummed any of you out or anything but I've always found the Escapist one of the better venues for discussion. Thoughts?