I suppose "sophistication" means different things to different people. I don't see anything sophisticated about the techniques used at Columbine or Aurora. What I do see is an unsophisticated focus on equipment (either type or sheer numbers) and little attention to anything else. Their choices seem to be based upon TV and movie references, and little else.
I have yet to hear of a single such attacker who was especially skilled or who even attended a single training class or shooting match. If there were training videos found in someone's apartment, it would be common knowledge by now. The concern seems unwarranted as such.
It doesn't take much of an advantage to dominate those unarmed and untrained.