Re: Training at Hombu - is it worth it?
I would like to make a number of points.
The Hombu is a very large dojo/organization and many expatriate friends of mine were intially disconcerted by its impersonal, factory-like atmosphere. It is definitely not a 'local' dojo, so you should not expect to encounter a similar atmosphere. I myself preferred training there when the teachers I know/knew well used to teach there: Yamaguchi, Arikawa and Tada. I do not know the present generation of instructors so well. Of course, I know them to talk to and pass the time of day with, but I do not know their keiko as well as I knew that of Kisshomaru Doshu and the deshi I mentioned above.
When I came to Japan in 1980, I had limited choice concerning where I would work. Tokyo was not an option and I had to choose between Hiroshima, Sendai and Oita. Training-wise, the least attractive option would have been Oita, since the nearest aikido shihan whom I knew was any good was Morito Suganuma in Fukuoka. Sendai is part of the Tohoku federation and had massive technical input from Shirata, Saito and their advanced disciples. I chose Hiroshima and was fortunate to meet the local aikido instructor, a no-nonsense technician who also dabbled in DRAJJ and who had little time for theory. The people with whom I trained over the years are now good friends and, also, have opened their own dojo. I think this is part of what happens when you train for a number of decades and keep at it. So, apart from training in my own dojo, I could train somewhere, with friends whose training regime I like and accept, on any evening of the week.
I would not pay much attention to Tokyo/Osaka rivalry. This has been a tradition since long before aikido was created and aikido has added to it here as it has with Mito/Iwama .However, I am not advertising Hiroshima as a place to live and train. It is an 'average' provincial city and the aikido 'politics' here are as intrusive as they are unwelcome. But you will encounter 'politics' in any dojo, certainly in the Hombu. Of course, there are a number of very good places in Tokyo to train, in additon to the Hombu.