I'm wondering if any of you with karate experience might want to share your opinions on cross-training in karate and aikido.
Firstly, I'd say that in my experience getting a firm grounding in one art before starting to train in others is quite important.
Secondly, most karate is taught in a very linear manner (even "Okinawan" styles). This is a hangover from when it was modified to be taught in Okinawan schools back before the First World War, and dozens of students only had room to march up and down the dojo in straight lines. It is also one of the great weaknesses of karate as it is now taught. OTOH, most styles will teach you to strike and punch properly, which is the great weakness of most aikido people. And not just from a self-defence POV - better strikes give your partners a better practice.
But, as always, the instructor is more important than the style, or even the art.