No you won't get any reward from musing for delegating any steempower to them. I'm not entirely sure what musing's business model is exactly but I know that it has nothing to do with rewarding people for delegating steempower to them.
With that in mind, you could still delegate some of your steempower to musing; if you feel that musing has done alot for you, and I'm sure it has, then I don't think it's a bad idea. I plan to delegate a little steempower to them soon, even though I don't have much, at the very least, it would be my way of saying thank you to them.