My karate training has increased my strength and stamina LOTS. Without that, I wouldn't be able to make it through our intense aikido practices. And after learning karate breakfalls, ukemi was nothing to fear. Karate training also gave me a headstart on learning how to focus on what's important in training.
My sensei would be a better judge, but I think I focus completely on aikido during practice without letting karate "corrupt" it.
But my long karate stances keep showing up in my tai chi, causing my tai chi instructor to comment every so often that that's the hardest habit to break.