If you're going to have 12 people over, you'll be double-checking the dishes well before the day of the party. Worst comes to worse, you hit the store and buy a new set of utensils. For that matter, since you'd be okay with mixing in the everyday utensils you're scared of giving up, you can just get whatever you're missing from the thriftstore.
Plus, let's say you do end up missing a salad fork. Don't serve a course that calls for salad forks!
Really don't see how this is any different from breaking a plate or bowl. What would you do if that happened right before a big party? Do that.
As for getting dull, if they aren't silver, they won't, if they are, they'll polish.