A person steals a beam to build a house. The Torah says: Dismantle the house and give the beam back to its owner:
When one has sinned, he realizes his guilt and restores what he got through robbery or fraud. [Lev. 5:23]
Bet Shammai said: Follow Torah law. But Bet Hillel said that the financial loss to the thief is so high it might impede his repentance, which is the purpose of justice, so financial compensation is enough. Bet Hillel’s ruling prevailed. [Gittin 55a, Tosefta Bava Kamma 10:5]
Talmud even reports that the King of Nineveh wanted his people to repent so completely that they should tear down their houses to return stolen beams, so as not to own a stolen object! [Taanit 16a]
The Mishna concludes:
This is the general rule: all robbers make restitution according to [the value of the stolen object] at the moment of theft. [Mishna, Bava Kamma 9:1]
Now my question. Does the victim have any say in the matter? Maybe whatever was stolen from him has special, sentimental value, and he wants it back, not money; and it is possible to give it back to him, even though the cost to the thief is high. Would this be resolved on a case-by-case basis or is Hillel's ruling automatically applied? As it stands, Hillel's ruling seems to imply: "Steal whatever you want and pay back its monetary value".
Case added in view of comments. You own an old, battered spoon that used to belong to your great-grandfather in the old country and is of great sentimental value to you. It is stolen from you and the thief makes it the centerpiece of a work of modern art called "The Old Country", which becomes very popular and is worth millions. (Preposterous? See here.) You recognize your spoon and demand it back. Shammai says: Give it back. Hillel says: Give back the value of the spoon (10 cents). What is the halacha?