For rapid steel removal, it is darn hard to beat the Pferd 14" chip breaker, from Amazon. All Pferd and Grobet files are top of the line. Simonds is a more affordable file that is WAY better than the new Nicholsons. I buy Pferd and Simonds from Amazon.
The problem with new Nicholsons are they are made in Mexico and some in brazil. The quality control is absent. Old Nicholson files are great...new ones not great at all.