Although modulars are great for the comfort options offered, they are not as reliable, protection-wise, as a std. full face helmet in a bad get off/impact. Due to their mechanical design, they lack the structural integrity of the std design, however they certainly afford more protection than a half or three-quarter design.
I have seen several modular helmets firsthand that did not save their users in bad accidents. I'm not saying that they are a bad choice, but that potential users should be aware of the greater risks associated with them. Conversely, I have had the sad experience of being in two accidents where both of my bikes were totaled. In the first one, I certainly would have died instantly if it were not for wearing a full faced lid (an Arai). In the second instance, were it not for my Bell Star, I would have incurred a severe head trauma injury. In both cases I sufffered no head injuries whatsoever, no headaches, bruises or even any soreness!