Looking to upgrade my back surround sound speakers

I find the rear speakers are only marginally important. The small quantity of the sound directed to them (usually), seems to make them pretty insignificant in th broad scheme of things in 5.1 sound
I could very well be wrong on that, but I would not spend much on the rears.
The front, center ,and sub are the biggies IMO.
For a seamless presentation though, they should be the same brand/ series.

Thx Liz, I called ML and they recommended the Motion FX line for my application.

I'd go with ML, too. This will keep the voicing the same throughout the system, very important for a seamless flow from front to rear...

-RW-

I would buy some used script i's. Those were fantastic srrounds and I love the design.

Dont get crazy on this idea of voicing for rears surrounds as noted its not exactly in your face sound. The content will be ambient, add space and depth with some affects mixed in. There is no need to be anal about them, as long as they are in the general ballpark you will be just fine.
I used B&W surrounds with Innersound Eros so I speak from almost exact experience. Also at that distance its questionable as to the need at all but I would do it if thats what you want, just place them high on wall so the dont call placement attention to themselves.