Recently saw a video about an interview with the Legend Philippe Dufour.
One of the point he mentioned was that he will never choose a silicon hairspring over the conventional ones is that the former isn't serviceable. Let's say your grandson/daughter found your watch 50 years down the road and it has a broken silicon hairspring. It will not be serviceable and the whole part need to be replaced. On the other hand, if it has a conventional hairspring, a good watchmaker can always tune it back/carry out repair work and get that vintage watch running again.
That being said, he isn't against silicon hairspring and also acknowledged all the merits of it. From anti magnetism to the innovation etc...