I hate to just throw the question right back at you, but honestly the only real determining factor is, is it worth it to you? Colouring is a lot of work, so is it worth it to you to see your work in full-colour? Or does the work look just as nice and work well in partial-colour to you? How much time does doing it in partial colour actually save you?
That question's gonna have different answers for different folks, and for different comics. It's important to me for my current fantasy comic to be in full colour, because colour is a big part of the magic and the feeling of the world. Doing it in black-and-white would feel like I wasn't really making the thing I wanted to make. But when I was doing an autobio comic, some people asked me if I had ever thought about colouring it, and I was basically like, "no, it might look cool but it wouldn't make the comic BETTER really, it would just mean it'd take more time to finish," so for that comic it wasn't worth it.
So I think that's the question, ultimately -- how important is colour for this comic, to you?