I haven't done it myself, but has anyone ever used one of those do-it-yourself gun bluing kits, and if so do you think it would be an option if someone wanted to coat one of their DCs?

Personally, unless you're going to be using these in a salt water/swamp/jungle environment, I think wiping it off after use and running a (Sentry) Marine Tuf Cloth every over it so often should be plenty of maintenance to keep your knife purty. I like the Double Cut finish a lot more than coated blades, but I don't need that corrosion protection.