Yes, slugs will be fine in this shotgun. Just don't forget to change the gas valve when you go back for grouse or clays.
Another one to look at is the new Remington V3. No gas valve, less recoil. It is a little bit more expensive but so far I'm happy I got rid of my SA08. It's also drilled for a rail for mounting a scope or a red dot or whatever you want to use.
However, none of that matters if the shotgun doesn't fit well.