This is a touchy subject, but one that absolutely deserves to be examined. I have noticed that on several message boards, students of aiki arts other than O'Sensei's aikido are ridiculed as "not being real aikido," or "copycats." Of course this is usually done by those in aikido dojos who are not aware that there are aiki arts that preceeded O'Sensei, (some of which he studied, such as Daito ryu).
I am currently a student in a dojo where we train in Nihon Goshin Aikido (NGA), an art created by Shodo Morita, a contemporary of O'Sensei who studied Daito ryu, among other arts. The name "Nihon Goshin Aikido" was created by Sensei Morita and used officially in the 1940s in his dojo, and continues in the United States today. While NGA may have similarities to Ueshiba's aikido, it is quite different, and all who practice it are very upfront about it.
Frequently, I have seen negative posts about NGA and other aiki arts that are not derived from O'Sensei. As far as I'm concerned, those posting are uninformed and intolerant. I know this is not the way of most enlightened aikidoka, and it is clear that other aiki arts are appreciated by the highest levels in the organizations of O'Sensei's aikido. As an example, the Aiki Expo this year will feature as one of its teachers a phenomenal Sensei, Don Angier of Shidare Yanagi ryu, Aikijujitsu.
I am interested in hearing what others have to say on this issue. Personally, I believe we have more to gain by observing each other and our similarities, rather than disparaging another's art as inferior or not "true" aiki.