Perhaps it is more fair to his memory to judge, or discuss his teaching abilities from the period when he was actually teaching.
The era in which he actively taught he produced some remarkable men; Inue, Shirata, Mochizuki, Tomiki, Shioda, Hisa etc. These men were pretty substantial in their day.
Takuma Hisa is exactly the person I was thinking of. He learned Daito Ryu from Morihei Ueshiba first, then
Sokaku Takeda. He didn't seem to find anything wrong with Osensei's pedagogy. He even ended up calling what he was teaching "aikido" and insisted it was the same thing.
If things did change, what were they? The fusion with Omoto-beliefs perhaps or is it just a case that he wasn't teaching much later on. I recall an interview with Takuma Hisa in which he had something to say about Takeda Sensei's own enlightenment, not totally dissimilar to Osensei's.