But the question still remains: can concurrent cross-training in another art help us or will it only confuse us?
I think it really depends on the person and the way that they train.
Cross-training doesn't necessarily mean that you're waffling between two activities. Many atheletes cross-train in order to enhance their performance in their "main" sport. Many martial artists do the same by going to different arts and looking at it, for example, with an aikidoka's eyes. This doesn't mean that they necessarily come to the art with preconceptions and expectations but rather think about it in terms of aikido.
There are plenty of people I know in aikido who dabble in jujutsu, judo, karate, iaido, jodo, and other arts; I've had a bit of experience in all of the above while or before doing aikido and believe it's provided me with tools and ways of thinking that has helped my aikido.