Unfortunately the apparently sharp definition between types of martial art makes is think that some techniques are better than others etc. One of the beauties of fighting is that it is so dynamic. Sometimes just grabbing someones balls really hard can incapacitate them. Although martial arts can help you to identify weak spots and also techniques which allow you to take advantage of the situation the best technique is the one that 'works' at the time. Although you can say some techniques are invariabily more likely to be effective, it depends who you are fighting, on what they expect etc. However, at higher levels martial artists generally see a bit of other martial arts either in their own martial art or through training to defend against them anyway.
For this reason, when fighting someone with a broader experience of fighting or martial arts it is harder to do something they don't expect, unless they train with restrictions (e.g. a kick to the knee/balls or an attack from behind is a good way to deal someone with no experience outside boxing).
Although we stand behind the 'aikido' front, each of our abilities in self defence is very different. Aikido provides a useful way to analyse combat and work through realistic self-defence situations. Whether it works or not very much depends on your physical ability (not particularly strength, but the ability of your body to react in an effective way).