Roy Klein wrote:
But if training in a slightly different aikido is confusing, wouldn't training in something completely different be even more so, atleast for a beginner?
Well, Roy, if someone gets confused, I would recommend to stop cross training until he is firm enough in one art.
And directly to your question, it is very difficult to generalise.
For example when I was at school most people did not have problems having maths in one class and history right in the next one, unless they had generally problems with one of them. They are both totally different.
Some people had problems with two different foreign languages directly one after the other, some had problems with maths and physics one after the other, while other students did not face those problems.
So just an idea is that totally different things do not interfere. If they are similar and you have significant problems, you might get confused by too similar environments. If you are doing good in one a similar one could help improving your knowledge in both.
Back to MA. Again, if one faces serious problems, he/she should not multiply them by cross training. If not one should look what is missing, what is lacking. I would recommend any kihon waza (basic technical skills), if you feel you are missing something ("I need kicks") or if you feel, your attacks are not trained well in your aikido class, but need improvement.
Fighting in judo, karate, ju jutsu or kung fu, arnis, bjj, etc. is mostly fine, while I would not comment fighting in competition or preparation for championships. But which one is good or not depends on each one's personality.
And it is a totally different discussion, if someone asks for something additional because of only few aikido classes in the local dojo - as it is here if I recall right - or if one could practise aikido 7 days a week, twice or three times a day, but asks if he/she should add something different.