DS
I'm guessing anyone who knows sith magic is familiar with the technique.
Why?
Consider how few people actually practiced Sith magic with any degree of proficiency; the Ketos, Kun, Nadd, Zannah, presumably a host of ancient Sith, and some random Bothan shown on the Wikia. Aleema Keto used the power to no effect against Exar Kun before he reaches his peak. I had already assumed that the ancients were familiar with the ability, considering it'd been passed down through the amulets. Zannah is given a scroll detailing the use of a select few spells, IIRC, and Bane himself is entirely unfamiliar with the brand of Force use.
Kun's amulet still amplifies the power of the blasts exponentially, which is an advantage other potential practitioners of the technique don't have. At the end of the day, I'm not seeing the changes.