Oh, it's not important to keep it, particularly. I always dye my hair normal colors for customer visits at my current job, even though every boss I've ever had has told me it wasn't worth the bother to do. I just think it would be kind of fun. I actually do err on the side of dressy already, for similar reasons (mild fear of overfreakiness), and that drives my urge to dye.

Basically: I think that most people who I'd care to work for would see it as neutral and far outweighed by other considerations (like the ones you list). I think I'd feel that way if I were hiring, too, so I'm going to keep it this color for a while. The thing is, my impulse to dye it back is SO STRONG that I think I have to NOT do it just to see how I feel. :)

(For me: it depends on how they pull off the hair, actually.)