Occasionally I'll see a smaller 4 piston caliper on the LF on a nonwing sprint car. Has anyone out there seen any benefit to this? Maybe get a tight car turned on a dry slick track?

Not sure what you are asking, a caliper is common on the left front, has been since time began.

I'm referring to a 4 piston caliper being more aggressive than a 1 or 2 piston design which is the standard on most sprint cars.

Right, it's going to help it turn in.

Run a proportioning valve so you can take brake away from that corner when you don't want it. At that point all you're out is the extra weight of the heavier caliper.

I don't think I have ever seen a tight car on a dry slick track.