Plus a 7 inch angle grinder with a cup brush will remove rust faster then a needle scaler. (I think)
/QUOTE]
Can't comment on the speed of the removal but my wire brushes were always worn out with all the broke off bristtles setting my coveralls or leg. They were also harder to handle. Course I'm not very strong.
With the proper air compressor the needle scaler would be my choice. My air compressor is only 2 HP. , I think, with 2.5 HP on the side and the salesman telling me it was actually rated at three HP. With full pressure it's quite impressive at start up and for the next 15 seconds. Then it slows down to a mediocre rate and takes longer.
The scalers seem to work better on the layered up rust that has real hard sports in it.