Let's take a look at the situation where you might want to sacrifice your Rook.
As mentioned before, promoting pawn is a big gain.
Well, this is an ideal development( Gold + Rook promotion - Pawn =12 points). Of course unless your opponent is a beginner, this is not something that is going to happen.
Single strike of pawn at the head of Rook
Remember this pawn drop. This technique can be very useful.
Silver advance to threat Rook and promoted pawn
Decision point. you can retreat your Rook but then you will lose that precious promoted pawn.
So Sente goes for all the way..
So how will you judge this exchange? Pawn promotion+Gold+Pawn-Rook=(6+5-1-10)=0, therefore point-wise, this is an even trade. However, in the real game, this amount of piece exchanges rarely amount to "even trade" It all depends on how the promoted pawn can be utilized, as if Sente slows down, Gote can drop the Rook at Sente's camp and easily regain other pieces.