Ill add one more thing.
In regards to does Aikido work in a MMA type situation, you have to realize that you have guys who have trained daily...
... they have had their thighs kicked repeatedly by someones shins, and have had their stomachs punched continually, etc. - all to 'toughen up their bodies.'
Then you have black belts of Aikido who cant even run a quarter of a mile without being winded, etc.
Point is that it is unrealistic to believe that someone who has not undergone a tough training cycle, nor subjected their body to such rigorous abuse with the goal of toughening it up... [regardless of if you agree with this concept of training or not]... how are they to fair against someone who has?
I think this is the one point that people tend to stick to when they think of Aikido as ineffective. Sure its limited to the aspect of sport fighting, but within that aspect one must concede that in such a scenario they are correct. [unless their are some 'magic' powers at work, then the guy in shape has more than the upper hand.]
Aikido could do with a bit more conditioning. Im not saying break the body, leave that to those who wish to do such training, but I have seen many examples of out of shape people who move up the ranks... This shouldnt be the case, and thats regardless of if you want to sport fight or just use Aikido as a meditative practice.
In a way Im sure this goes a long way in the rep that Aikido has gotten, even in yoga people are left in a better condition than when they came. [not the best way to phrase it, but the pointer is there.]
Peace
dAlen