Oh go on then Jon I'll chip in...
Or, maybe you don't yet have exposure to the various aiki models. What is your perception of the training? Why does it interest you enough to participate in discussion about it?
I think I have some exposure to some, but I'm not sure yet. I guess I'm interested in it for the same reasons I'm interested in the other MA I practice, something interesting me and the wife can do together when the kids have left home.
What are the specific elements that you feel affect the validity of the model(s)?
efficacy, what I can see, what I can feel, whether it can be articulated by its chief practitioners in terms that make sense to me (without lots of metaphysical hyperbole) but that aren't exclusive (my way is the only way that works) or proprietorial (my way requires at least minimum attendance at x seminars at y cost)
What would change your opinion?
I don't have strongly formed opinions yet, just a set of criteria by which to form them, keen interest and a sense that there's probably something going on based on what I've seen and read and experienced in my own practice.
Are these measures of validity consistent with your exposure to other training models within Aikido?
Not just consistent with, they are strongly informed by it, our society practices a hybrid Aikido from a diverse lineage (Tohei, Chiba, Tamura), and borrows from others such as Nishio, is interested in what works and is practical, and consistently challenges assumptions then changes things when needed. It is also distinctly not about making money, marketing itself, establishing a brand, etc. I've encountered that approach in CMA and voted with my feet pretty quickly.
We started taiji and qikung practice shortly before starting Aikido, We find points of comparison and relevance to our Aikido every time we practice tj/qk and especially when we come across a new posture or exercise, to me the connections seem abundant and obvious. We practice with a 5th dan who has more than 20 years in both arts and is a great source of insight. We also practice with senior dan grades who as far as I know have never practiced any CMA or anything that would be understood as part of the IP/IS movement who nevertheless display shed loads of something pretty profound. The extent to which these guys manifest aiki or IS/IP would have to be judged by those who have a clearer definition of those concepts than I do at present getting on the mat with them.