Interesting. I thought I started a thread on this topic a month or two ago. Anyway, for what it's worth, our head instructor, the late Akira Tohei Sensei, pointed out to us once in a discussion session that it is inappropriate for us as students to refer to ourselves as "aikidoka." This is because, as Jun pointed out, the term connotates someone who has dedicated their life to aikido and makes a living as an instructor in the art. This point was confirmed again later by our current Dojo Cho, Mrs. J.K. Tohei, who stated that we should refer to ourselves as "aikidoists," or "students of aikido." Obviously, people can and do call themselves what they wish, but this is what appears to be traditionally, technically, and gramatically correct. You may argue what you believe is appropriate, but I think I will go along with the people who I know are much more knowledgeable than me about the correct use and translation of the Japanese language.
By the way there are other martial artists which use the **ist suffix. I know that practitioners of American Kenpo (Ed Parker system) refer to themselves as kenpoists.
[Edited by BC on September 21, 2000 at 02:24pm]