This technique is a quote from Fletcher I read recently. It specifically was in reference to a Neumann SM26 but could be utilized with any pair of mic's one could place in a coincident array. The easiest way I have to do utilize this (without a SM26) is with a pair of SDC mated with an AKG H300. I've used the H300 with AT4051's as well as AKG C391/392/393/394 (not at once!) for M/S as well as ORTF & NOS & Blumlein & DIN. It had never occurred to me to track a vocalist that way. Another implementation would be by using a Sabra-Som ST4 vertically and placing two medium or large condensers in coincident mode. Actually that is what I use to get my R101's in Blumlein or M/S. I love learning new stuff.