I might be tempted to conserve it if it were mine. I think the grade suffered due to the negative eye appeal of the spotting. A heavily diluted dip might help to at least lighten up those dark spots. But then again, since it's not raw, I'd more than likely just leave it alone. I just fret about cracking holders. LOL
I was going to guess MS-66. I see someone mentioned about having the coin conserved. I was going to just sending it to NCS and see what people thought, is this a good candidate for conservation/professional cleaning.