Evidence like, for instance, today's equivalent feats of solidly beating a top Sumo guy in front of a multitude? trashing the Kodokan? being hired by Nakano School to teach combatives to high level spec-ops operatives? Because that is what aiki guys of yore is said they did. What are the martial feats of contemporary aiki proponents?
If these kind of entertaining discussions are still running, its your (pl) fault. Stop making excuses and running in semantic circles and start taking Naga/UFC/Olympics/Dog Bros gatherings/etc. by storm.for these are today's minimum standards of martial skill for everybody.
If you (pl) succeed, in a couple of days no sane individual will say there's no clear evidence availabe about the value of IS/IP/Aiki/wateverthename in martial arts. If you fail, you at least will have well deserved respect for trying. That's all.
Again, it seems that a higher bar is being set than is for conventional Aikido. Conventional Aikido folks say (mostly) that they're already able to do what Ueshiba did - which would include those feats, anybody calling for them to prove it in the UFC?
FWIW, I've got my share of stories (including some high level spec-ops stories), but it's better, IMO, to just go out and try for yourself.