Street attacks are 99% emotionally based. No offence, but it would be mighty hard to think underhooks, overhooks, guillotine or w/e.. when faced with an extremely angry person screaming obscenities then proceding to attack you.
In a gym or in training, you have consent, awareness, safety of knowing the guy wont pull a knife when you tap from an armbar or get TKO'd or even need a break.. you know? None of those are gauruntees in the street. You never know if the guy has friends, or has a weapon.
My advice is go ape shit. rip out eyes, hair, ears (it only takes 7 pounds of pressure to tear off a human ear) take out the throat, bend anything the way its not supposed to go. nomsayin? Just go fearal. Switch the predator to prey mentality and just go fuckin crazy. Thats what I'd do. I remember reading a story of a mother and daughter who's house was broken into. They came home, the robber saw them, grabbed a fire poker and started swinging. He broke the mothers arm and fractured her skull. He then grabbed the daughter and slammed her through the drywall. The mother, seeing this, gets up and goes fucking crazy. Jumps on the robber, and just starts ripping and tearing at anything she can. the robber, scared shitless runs away. We should be taking self defense from that girl instead of 99% of people who claim to know.
And I don't care if someone says its a "cheap shot" or whatever. I'm not gonna let some stranger (who mind you, i don't know if they have a weapon or friends around) fuck with my life, my job that I've worked so hard for, my education; I'll do whatever it takes to make sure my physical well being is not tampered with. If that means some groin shots, then so be it. I bet everyone has seen the video of the chinese guy getting mugged by now, I don't think anyone would have called cheap shot had the victim kicked the other guys in the nuts and tore out some eyes to get away. I would have commended it.