forward radiating surr speakers: yes or no?

I currently use Wharfedale Evo 8\'s for fronts. The rear surrounds are the matching DFS units that are of the bi-polar type. I'd have to say I use my system more for music than movies, & I love the sound from DVD-Audio discs. Should I switch the DFS units for a second pair of Evo 8's to act as my surrounds? What would doing this mean to movie soundtracks?