Currently riding with SPD pedals and specialized MTB shoes on my Supersix. I am considering getting SPD-SL's and carbon road shoes. Am I likely to notice/experience any difference with new pedals/shoes?

I did do a search and I know that the SPD-SL provides a bigger platform that SPD's and theoretically a more efficient power transfer. Are carbon shoes that much stiffer than non-carbon so as to make any difference?