So, although I really appreciate all the in-depth information provided in this thread, as one who currently trains in Aikido, it leaves me with some curious conclusions:
1. Daito Ryu, and Aikido to an even greater extent, are strange and weird systems of jujutsu that have no combative or self-defense value, and, in addition, have huge technical holes in them.
2. Aiki is basically extinct from modern Aikido and only a few individuals possess any accurate knowledge on how to foment such ability within the practitioner. This is akin to being able to actually find an authentic Koryu teacher or ryu-ha in the U.S. (few and far between).
3. The development of Aiki, or "Inner Strength" is better achieved through Chinese systems of practice.
4. That DR or Aikido are not even very effective ways to deliver this Aiki or "Inner Strength." One would be much better served with a more direct "fighting system."
This is not meant in a mean-spirited way at all, but, is this what we are getting at here?
I shan't speak for anyone else, but here's my take - which is the thrust of my book. Following caveats which may, by now, be unnecessary. I have never practiced Daito-ryu and had about five, albeit very intense years of training in aikido back in the 1970's. My training and perspective is informed largely from other martial arts.
#1 - DR and aikido ARE strange and weird systems. They are not koryu, which means that they are not congruent with a traditional Japanese culture when the martial arts fully fit the society they were in. They are also not simply practical systems - which makes them strange. BUT - both a) have in different ways, emerged from and have "transcended" the traditional culture from which they emerged. b) Have many values aside from "self-defense," - and these values are unique to each martial art c) Very definitely CAN have extreme value as self-defense or fighting arts, whether or not they would equal muay thai in a ring, or CQB for the battlefield. As I wrote in my first book, Dueling with OSensei, what if you gave everything you had to aikido - what if you practiced shomen-uchi and yokomen-uchi three hours a day, for example? Just that. And learned to put your whole body behind it, without overstriking, and using the off-hand to protect yourself. That there are far more efficient ways to learn to fight (in whatever venue you choose) is without doubt, in my view. But I could run a list of aikidoka, for example, whom I would NEVER want to fight - and I'm selecting them from among people who had little or no outside martial arts training (not the aikidoka who also did x martial art).
#2 YES! That's why I wrote the book - what I desired in aikido was the gold. When I found that, for me, there was good copper only, I went elsewhere. What stunned me was, now 20+ years after quitting, the realization that the gold HAD been there, buried and was largely lost/ignored. Simultaneously buried to an almost unreachable level and right on the surface all along. But I wrote my book to wake up and interest folks - in DR and in koryu as well, btw - that it is attainable not by demi-gods, but by US. And although there are few teachers who "have it" or even cared (otherwise, they would have "stolen" it, one way or another, even if Ueshiba wasn't teaching it explicitly), it can still be learned and recovered and returned in one form or another - to aikido, and I would imagine, if desired, to Daito-ryu as well.
#3 - No. Not necessarily. Man, the b.s. in Chinese martial arts is eyebrow high. It is very difficult there as well to find a teacher who is versed in those skills, and willing to teach - really teach. There are, however, more than we can find - YET - in modern aikido and DR, in my opinion.
#4 - In HIPS, I referred to the waza as the bottle and the IT as the brandy - without a bottle, where is the liquid? On the floor.
IT alone does not do it (note an earlier, I think on this thread, mention of I-ch'uan). The various containers you choose are a matter of taste, personal prediliction, etc. The problem that CAN come up with an art like aikido or DR is that one can be led to spend so long on the container (which embodies the culture, the techniques and the worldview, which can be, in it's own right, of supreme value), that one is never taught or lacks an interest in the brandy/IT. There is absolutely NOTHING that forbids a teacher from introducing IT training from the first day. Still - MANY will not do it. I'd like to again mention a recent account from a prominent koryu headmaster - who has
IT - and explains
how necessary it is - and teaches
it clearly - yet most of his students don't practice the internal training exercises.
Anyway, IT + aikido could be done right away - not as a bonbon (called a gokui) given years and years later.
Sorry for the length, but I think your questions deserve to be treated with real respect.