Personnally I have never bought from Artcurial, Antiquorum or any other auction house. Let me explain why and her are the reasons why I will never do so:
-no possibility to open the watch or see the movement
-no real warranty such as an invoice from a watchmaker stating and confirming that the watch has been professionnally overhauled
-no possibility of a real judicial recourse if you have been scammed while the watch being a franken or a completely out of working order watch
-you have to add extra fees to the value of the watch you are paying
Antiquorum is now run by Romain Rea, I have seen some pieces in his shop which were very expensive for the condition they were in. Back in 1999, when I was starting to be in watches I went to one of his boutiques on the flea market in Clignancourt, I saw back then a Seamaster SHOM. I had a look at it and asked the salesman if it worked, he answered me yes. When I wound teh watch, it didn't work. So I asked the case back opener to check the movement with my watchmaking magnifying glass. The movement was not in pristine condition, the oils were dried and the o ring was dead. The asked price for a so called great condition watch was 2000 french francs which was a supposed bargain back then. But due to the beyond average condition of the watch, it wasn't. I have one vintage watch shop where I only purchase and give my watches for servicing which is Charly La Passion des Montres, the guy is a true passionnate watchmaker servicing his own watches and selling them (most of them are in pristine condition). I also have another watchmaker not far from me who does great work too. For rarer or more expensive timepieces, I hunt on chrono24, ebay and more occasionnally forums.
I will tell you another story of a friend who bought a 1968 space compax at an auction house10 years ago, he overpayed the price of the watch by 40%, not to mention that the so called "perfect condition running" watch was 40 sec per day fast and he had an overhaul bill of 1000€. He tried to prosecute the auction house but it was too late. It was his first and last auction house purchase
I am very nitpicking when it comes to buying watches, personnally you can tell me that a person is an expert at an auction but if the guy in question isn't a watchmaker, I will never purchase the watch from him. Even catawiki who does acutions, has a marriage auctions sales section!!!
I was reminded by an old friend: "Always buy the seller first, then buy the watch." Which is true. I am also not John D Rockfeller, so I prefer to be cautious and very thoughtful before spending serious money in a timepiece.