Hood Deflectors: Yay Or Nay?

My dad swears by them, and my accord that I bought used had some hood rust from rock chips whereas his accord of similar age didn't have any when he got rid of it. I plan on getting the clear bra but should I also spring for the hood deflector? I can't seem to find any FiSTs with one on, only lower spec ones.

Hood Deflectors: Yay Or Nay?