I think that would be an excellent option
, I have the RXFX with the MA 250HD fronts and the rear soundstage is very immersive.
In my current setup I have a rectangular room with these 3/4 they way down the room side on to the listening positions, it's excellent, you get a full 360 image from the sound, I keep toying with the idea of adding 2 more, but when I listen to how it sounds allready I think it may be a waste of money as my room is only 3.8m wide.
Hope this helps!