I'm another aikidoka. I've only trained with AAI/AAA affiliated dojos so far, although I attended one seminar of "realistic aikido" (didn't like it).
I've trained karate when I was a kid (elementary school), but had to quit after achieving 6th kyu due to time conflicts.
What is funny is that Aikido works the way I imagine drugs work: when I started I was exhausted after one hour's training. The second year I attended both the beginner's class (again) and the intermidiate class. This year, I'm attending all the classes offered at the dojo, and I'd take more if they offered them (and if I could fit them in my schedule...)