Floor vs Surround

[Smadawho]

Would using floor speakers as rear speakers in a 5.1 setup be superior to using the surround speakers? I am speaking of the Klipsch reference series specifically. I noticed on their website that their reccommended systems all make use of surround speakers. I use my system primarily for watching movies if that makes a difference. Also in the reference series what would you reccommend for use with an Onkyo 705?

Thanks in advance.