steve worcester
I think there needs to be some points of clarification here.

A negative rake scraper is really any scraper that has a bevel on both sides.
It is designed to lay flat on the tool rest. It can be used to shear scrape, i.e. to be tilted at a 45-60 degree angle (vertical) and used to shear scrape.
An NR scraper, definitely uses the burr to cut, the reason you use the side up, the one that was not against the wheel.

I use them all the time on my own work, maybe because it is easier to use for refining than a gouge, maybe because I am not as proficient in the deft handling and dainty-ness required for what I need it to do for the same maneuver I would use an NR scraper.