I have the have the RTi10s fronts, CSi5 center, and am using onkyo surrounds that were apart of a Home Theatre in a Box. I am now looking to upgrade them. Should I get the FXi5 or the RTi6 for surrounds. What difference would I get from using the fxi5's and using the rti6's. I am not sure if I am going to go with a 7.1 or a 6.1, so what do you think of using fxi5 for the sides and an rti6 as a rear in a 6.1 setup.