I have never understood the relationship people "play on" between Yoshinkan and Daito Ryu, they are nothing like each other (thinking of the Yoshinkan mats I have been on and the Shioda books).
I would think that this 'relationship' would be based on a two things:
1. Gozo Shioda was granted a license in (guess what) Daito ryu from Ueshiba
2. From my limited exposure to the techniques of the Mainline of Daito ryu under Kondo Sensei, there is a strong relationship between the yoshinkan and that branch in the kata themselves (contained in ikkajo and nikkajo at least), the nature of kata in practice, and the martial spirit.
There are other branches of Daito ryu (most of which I am not as familiar with) that do not strike me as having as strong a connection with the yoshinkan. Your experience, of course, might vary depending on a few different factors:
1) not being very familiar with the same branch of Daito ryu
2) not being very familiar with 'mainline' yoshinkan
3) simply approaching the whole issue from a different perspective
So that you (or anyone else) can understand my perspective a little better, I'll add that I am a yudansha in the yoshinkan (training consistantly about 8 years) and I have trained in several open seminars with Kondo Sensei (and hope to continue that training).
From what I have been told, O'sensei was very much into a section of the syllabus that contained techniques using Aiki (Aiki no justu) and that I believe was what he mainly worked on to create Aikido.
That is an interesting observation...from what I have seen, the actual techniques taught in aikido are more from what some would regard as the 'jujutsu' level techniqes in the ikkajo, nikkajo, sankajo and yonkajo catalogues of techniques. Pretty much all of the standard ikkyo, nikyo, sankyo, yonkyo variations are contained in some basic fashion in those catalogues. Not being very familiar with the higher levels of Daito ryu from a practical viewpoint, I can't really speak to the Aiki no Jutsu techniques. And I have to wonder of the people making the claim that aikido is aiki no jutsu...what is their basis for comparison? What is their specific exposure to the Aiki no Jutsu of Daito ryu?
I do know that when Kondo Sensei teaches from Ikkajo, he stresses where and when specifically 'aiki' could be applied, trnsforming the techinques from jujutsu to aikijujutsu.
In reading this thread I couldn't help but wonder of the aikidoka speaking of what they could get from Daito ryu training...how much training in any official branch they had actually had?