Surround speaker sugg. for Martin Logan fronts?

I recently purchased a pair of ML Quests here on Audiogon. I have a Martin Logan "cinema" center channel as well. I'm trying to find a pair of surround speakers that would match them. I know they make the scripts, but I don't think I could squeeze them in the back of my room. Room is 16 1/2 x 14 1/2 x 20 ft high. At the time the house was built, it was wired for side mounted surrounds about 9' high and 2 ft from back wall (just to side and back of sofa).

I've talked to several local dealers and they haven't given me any good answers..they just try to sell me what they have and "garuntee" it will work.

So far, I've been pointed to:
- B&W DS6 Dipoles (but they were discontinued)
- Boston Acoustic surrounds (can't remember model)
- ML Scripts "and just stick them back there"

Would anyone have any ideas? What are other people running?

How crucial is it to have them match sound wise?

I recently added Mirage Omisats (3) as surrounds with ML aerius and a cinema center. Haven't had them long but they appear to be a pretty good match since they are also bipolar. They are very small and can be wall, ceiling or stand mounted.
Well, I've got Scenarios "just stuck back there" and they do OK considering the crappy positioning. They're fine for movies, not so great for surround music, due to the setup. I have (slightly used) Scenarios because they cost me significantly less than new Scripts.

I also have used my older Triad Silver Surrounds with my mains - they work surprisingly well considering that they are supposedly completely incompatible wiht a 'static speaker. They're dipoles, BTW, and I had them ceiling mounted.
I've used Triad Silver's as well and they did work extremely well. My choice would probably be Scripts or other small ML speakers, but the room did not allow for those, so I went with ceiling mounted Triads. They did work very well with the MLs.
We've had very good luck using the ML scripts in strange rooms by firing them off side walls or in one case the ceiling, might be something to consider, although it certainly depends on the room.