Justin Smith wrote:
Smith, while valuing taijiquan, especially Zheng Manqing, seemed to not think much of aikido. I believe in Masters and Methods he dismisses it is so much daring-do, since he wasn't able to test Ueshiba, which is unfortunate.
Zheng Manqing (often spelled "Ch'eng Man Ching" in the Wade-Giles method) was a colorful character. He certainly had some qi skills, but I have no real idea of the extent of them... and his followers tend to muddy the waters by worshipping him as godlike.
There are some questions about Cheng's actual claims for his own training, but that to the side, Cheng was known on Taiwan as the painting teacher for Madame Chiang Kai Shek. Apparently a lot of the really well-known martial artists on Taiwan were forbidden to challenge Cheng because of that relationship to Madame Chiang.
When Chen was younger, he challenged some big names in Chinese martial arts and apparently was beaten badly a number of times. Smith refers briefly to an encounter Cheng had with the very famous Tu Xing Wu and says only that Cheng mentioned that he "could not escape Tu's foot", or something along those lines. In reality, Tu apparently put Cheng in the hospital for 3 months.
My perspective would be that Cheng had some skills, but not the top level a lot of people claim for him.... so any comments he may have made about being in a position to judge Ueshiba's skills should be viewed askance.