I would be concerned about removing metal from the crank due to balance issues. I have seen the cuts you refer to and they appear to be a good idea. In automotive Hot Rodding circles Knife edging a crank refers to cutting the flat of the counterweight down to a knife edge in order to sling off excess oil sticking to it which would add undesired weight. This in addition to a crankshaft scraper (hard to describe, a series of teeth that are fixed to the inside of the crankcase that are cut very close to the contour of the spinning crank and "scrapes" off the oil ) adds horsepower without stressing the engine. If you have ever seen the inside of the crankcase of an automotive engine running you would see strings of oil being flung off the crankshaft.