Yes you can put either an electric or a thicker non-electic insole in. The ones that come with them are pretty flimsy. They definitely seem to breath; among other things they allow for chemical hand warmers to be inserted into a pocket, and those only work if there is some oxygen available. In my experience, it's the bottoms of my feet that get the coldest, so a thicker insole or an electric insole is the key.

p3