I don't kow about the overall damage reduction, but for the way to kill a Charge, Targe, and Eyelander Demoman, we must look to the Heavy:
"Some people thinnk they can outsmart me. Hmm. I have yet to see one outsmart boolet"
Bullets the way to go against the super demos. They aren't really that OP, it's just that everyone is playing soldier and demo right now, and the Targe has explosion resistance. Once the update hype is over, the Targe n Eyelander Demo won't be nearly as powerful. I just hope the Targe and Eyelander don't get nerfed too bad, 'cause I rather enjoy the eyelander and targe.

Don't want another sandman, now do we?