Since I've never been on the mat with Arikawa Sensei, I have no plans to post in Ellis's original thread, but there is a fascinating YouTube video of Arikawa teaching in France in the early 1990s.
I find it interesting that he does several things that would get candidates for higher kyu grades failed in most organisations. His lack of outward zanshin, in the sense that this is normally taught in the Aikikai, is very noticeable to me after reading Ellis's article (although he does seem to be specifically teaching zanshin at 1:50). He hardly ever uses his spare hand, which dangles at his side for most of the time. It also surprised me that he often (see around 1:32, for instance, and just after the 3 minute mark) doesn't obviously unbalance his uke at the start of the technique, nor consistently keep control of uke's balance.
What is obvious, though, is the sheer crashing power of his irimi (see at around 2:07).
A scary guy, though I am disappointed not to have experienced his aikido. While I was at Hombu Dojo in 2003 I went in with trepidation to a class he was scheduled to teach, but I heard that he was already in hospital (for what turned out to be the last time).