Peter A Goldsbury
I am in my seventies, and I cannot use pure physical strength, so I have to use my entire body-mind, in ways that I still do not fully understand. Had you started training when M Sekiya spent his year in the UK?
No, I wasn't around when Sekiya Sensei was "in his prime", so to speak, although I did see him a couple of times when he returned to the UK in the years after he went back to Japan. He taught at a BAF Summer School a few years later, much to the disapproval of Hombu Dojo. I think Kanetsuka Sensei wanted somehow to recognise publicly Sekiya's influence on his own aikido, although the week turned out to be not the most harmonious, for various reasons.
I like two-person morotedori very much, and practise it often. It requires the two arms to work together but on different partners, and - as you say - you have to use sound principles as you can't use strength with big ukes. The tai-sabaki encapsulates for me so much of the essentials of aikido too: it is the same as you see O-Sensei doing when surrounded by attackers, where he seems to move in an instant to being outside the circle and behind one of the attackers.