that is the technique that is used in graphic arts copy cameras. works good when you get it correct.
BTW, EPY has a diffuse rms granularity of 11, so you'll have no worries about sharpness or grain. It's now a T-grain film which Kodak rates at 64. A freakin' razor already.
If your lights have standard 7 inch reflectors on them I would definitely use the feathering techique, but it's unnecessary with a softbox.