AIKIDO contains martial techniques from other arts such as DAITO-RYU Jujitsu, which from my understanding Mr. Sokaku Takeda had tested in combat. Not to mention, the techniques derived from the Samurai which were used to kill. And through my personal experience in the dojo, I have seen, or been shown many instances where there was the opportunity to seriously injure or kill the uke. I agree with Ms. Seiser that ""the "street effectivity" of any style has more to do with the psychology of the individual rather than the style.""
I believe that in AIKIDO, to be "street effective" takes on a whole new meaning, one which was defined when O Sensei re-defined his martial arts as "The Art of Peace".
So, in that manner, in order to be street-effective in the art of Aikido, one must realize that the goal, or purpose of Aikido is to create harmony, first within yourself to eliminate all thoughts of aggressiveness or a need for violence in any situation. Then, to create harmony with your uke so that you may execute these techniques in such a way that no one is harmed, not you, or your attacker. Finally, to create harmony with everyone around you, to reach out into the world and use your techniques to make it a place where violence and hate doesn't exist. This is TAKEMUSU AIKI.
So, to answer your question simply, yes, the techniques of AIKIDO can hurt, main, or kill someone in a fight on the street, but to DO AIKIDO means to perform these techniques with love and compassion, to take hate out of our hearts so that there is no fight.