i recently asked a similar question and the consensus was no. i ended up getting road shoes on sale anyway cause i had a set of pd-r540 pedals lying around that were gathering dust and i wanted click-adjustment on the top strap (which really has been fantastic). no difference in performance--definitely more annoying to clip in to, if anything. but now i have to play around with cleat cant all over again. aaargh.

those asking you what you are doing with mtb pedals on your road bike are just trolls. i would drop road pedalers all the time wearing my spds (okay, maybe only occasionally, but you get my point), and still get schooled by some friends wearing spds.