Re: Does one's size or weight affect one's Aikido?
Generally speaking, I think that the majority of us agree that being overweight is not necessarily an advantage in life or in Aikido.
But I would think that it is very true indeed that one's size and weight affect his/her Aikido. Of course they do. Whether they affect it for good or ill is up to the individual.
If someone is good enough, he or she will know how to use his/her body, mind, energy - entire being - to his/her advantage.
A general response to this and the other conversation regarding "large" Sensei: I don't see the productivity of having discussions about who is fat and why and whether or not they should do something about it. What is the point of that, aside to make oneself feel superior?
If you yourself are concerned with maintaining good fitness, then do so! If you are concerned with promoting fitness, then do so. Running about pointing out other people's obesity and shaking your head about it will not promote fitness or improve your Aikido, in my opinion.