To understand the significance of the 2012 live event, one must first understand its progenitor: Acceed (アクシード).
In the absence of detailed reviews, a picture of the "experience" can be pieced together from fan discussions and community archives. A comment on a BBS dedicated to the subject, stating, "SM LIVE 2012 was so tough to watch," gives a hint of the hardcore content that was likely on display, which was a hallmark of ACCEED's style. ACCEED SM LIVE 2012