Looking to upgrade my back surround sound speakers


I am looking to upgrade both my back surround sound speakers as part of my 5.1 setup. I currently have Martin Logan Spire as my L/R and the Martin Logan Encore as my center channel. Any suggestions? Should I keep with the Martin Logan brand...do they make dipole/bipole/monopole speakers?

I have a beam about 10 inches behind the listening area and a wall in which I would mount the rears. I prefer not to dig into the wall and thus prefer mounted speakers.
pig2fever
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.
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.