Re: Ikkyo from the guard
I know from my own experiences that there was a direct correalation to the crossover to BJJ with the basics of dynamic movment. However, given the pace and closer distance of BJJ, my responses and timing were not always correct. There were also some responses that I had yet to develop that we simply do not train in aikido.
I hesitate to say techniques. Once you start looking at techniques really everything becomes a variation of something we do in aikido. What is interesting is when you can recognize it!
For instance, I finally figured out that most sweeps from the bottom of the guard are basically the principle of irimi. uke is in your guard, and you must sweep him to either submission or to a side control or mount. If you look at the dynamics of what you must do...it is irimi! his energy is coming down on your hips to control you so he can pass, you shrimp you hips out (irimi) so his energy is now going in down into the mat into the "void".
So, what is different is not so much the principles, but the response, set up, timing, all that!
I would agree with Michael that in many respects striking arts are not so complimentary as they will deal more with striking force. That said, in Muay Thai, we still need to have proper footwork and responses that follow the same principles, but they are not so concerned with balance, blending, and redirecting energy to exploit. It is more of a "ground and pound" scenario.
Having studied karate for many years...it is there too, but the karate I studied as more about block and counter than anything else. I can now make slight adjustments to karate kata and it flows more like aiki.
But, I agree with Michael..on the scale..."striking arts" have less in common than say BJJ, Aikido, and Judo that operate off the same core with different methodologies that are complementary.