Much of Aikido is a distillation of Daito Ryu aiki jujutsu, an older complex art. Several Daito Ryu sites list over 2000 techniques to master before completing training. Nihon Goshin Aikido, an art formed by Shodo Morita (a contemporary of Ueshiba) is heavily based on aikijutsu/daito ryu. and has been talked about on a different thread on this forum. When you watch the techniques they tend to have more of an economy of movement than Ueshiba's-aikido. Blending is quick, smaller circles, the techniques end quickly too, but beautiful in their efficiency. The style is harder than aikikai as well.
If I ever have time, I would love to explore authentic daito-ryu aikijutsu further.
"B: How many techniques are there in Aikido?
O Sensei: There are about 3,000 basic techniques, and each one of them has 16 variations . . . so there are many thousands. Depending on the situation, you create new ones."
Who have you watched who had greater economy of movement than Ueshiba?
I used to be a bit interested in Daito Ryu too, but there's plenty Aikido I'll never have enough time to learn and now I'm happy to just chase after that.