Re: significance to testing/belt rank?
I don't understand where you get the restriction on practicing certain techniques not being allowed. If you are referring to testing, yes that is probably true. However, my beginning students practice everything up to and including henka waza and kaeshi waza as they progress. I have had non-ranked students involved in such classes as well to reinforce their kihon waza.
True there is politics in aikido-one of the reasons I left an organization. However, to me the koryu approach and the kyu/dan system approach are just different themes on the same transmission of knowledge.