Re: Crosstraining Aikidoka: A Survey
A lot of the martial arts have changed and are less complete than what they once were. Karate originally had grappling in it and throws before it became mainly punching and kicking. Judo had atemi (striking) in it, a lot more ne-waza, leg locks, neck cranks. The standard of atemi in aikido is now often rather low.
So really to do your martial art properly, you need to cross-train. To become skilled at the striking component in aikido and to learn the atemi component of judo, you really need to study something like karate (perhaps goju ryu). To become skilled at ne-waza (groundwork) in judo you really need to cross train in BJJ. To be good on your feet at BJJ you really need to train in judo.
Tomiki aikido was intended to be practised with judo. Many of the standing joint techniques would be studied doing aikido and also the techniques from a greater distance, whereas judo would cover the closer-in throws where you grab the gi.
I tend to call this compartmentalization of martial arts training. You need to go to the different martial arts to become proficient in the area that they specialize in. The problem is that you don't usually have enough time (or inclination) to train 12 sessions per week covering all the areas you need to cover. On the other hand, a problem with cross-training is that many become jack of all trades and king of none.