In an older thread on the subject it was pointed out that the whole business of down-tuning 12-strings was to compensate for the comparatively poorly reinforced necks (and in some instances, bodies,) of some of the earlier models. I believe I am safe in saying that virtually all 12's manufactured after about 1970 have more improved reinforcements. They don't require down-tuning. However, having said that, I know that some folks simply like the sound of the down-tuned 12's, especially when capoed.