Alright, so the company I work for (ooh yeah entry level helper :P) installs ducts in both the attic and basement. We also install 2 units, one in the basement (if applicable) and one in the attic. Seems logical for a 2 story house, but I've been looking/researching around and have been hearing of how installing ducts in the attic isn't very efficient. We do insulate our ducts with R8 duct wrap, and paint (mastic) the seams where the drives meet. My question is, is there a more efficient way to cool/heat a 2 story house besides putting the unit(s) in the basement and/or attic?