A lightened crank will make the engine rev noticably faster (along with light pistons and rods). The crank in my 474 R3W9 motor was 4.375 stroke (More than even some big block strokers). The crank was 45 pounds with 340 mains. Rods were 618 Grams/6.300 and pistons were 430 grams / 4.155 bore. But that thing revved like crazy. I literally made a Baby cry when the car had the 3-1/2" FLOWMASTERS on it, and kids were constanly asking me to rev it when I was at the track.

My take on performance is that the engine will react faster and so it will flash the converter a little faster and hit the tires a little faster. So if you needed to make the CAR react a little faster for some reason it would be an advantage. I am sure the engine will accelerate the car a little faster but it would be in the hundredths. Not much. If you are making a lot of HP the car and crank are just going to accelerate fast no matter what. So a heavy crank in a motor / car that has a lot of HP is not going to be a disadvantage.

But I would have all 4 rod pins drilled no matter what, because this is bad weight and will not help crankshaft strength at all. I also would still go for lighter weight rods and pistons as long as the cost or strength are not to the extreme. Lighter pistons and rods are easier on the crank and them selves. Especially important if you want to turn higher RPM.