Like you, I do not understand what may be wrong with stacking M4OHN and 4-AD, especially if the 4-AD is a transdermal (one less pass through the liver). FWIW, this stack seems OK to me. Perhaps the problem is due to M4OHN being considered more of a cutting compound and 4-AD more of a bulker, but that does not put the combination into the "be careful" category.