Different brand for Wides/Heights

I have a Onkyo 709 and 7.1 Atlantic Tech 2400 -
I am thinking about picking up another set of the LR's to run as front wide/front high so I can switch between those and the rears just to see what I like.

I already have an extra Center Channel that is exactly same as system - are the height channels in plz and dsx truly stereo, or could I run a height center.

Or I could put the center in the rear (THX-ish style) and put the LR's in the height or wide to see what it's like.

Which would you do out of these...
Center height - LR rear - uses speakers i already have
Center rear - LR height/wide - uses speakers i already have
LR Height/Wide - LR Center - requires spending $$ on another set

Any real downside to mono rear instead of "stereo" - they are currently positioned like 3.5 ft apart - closer to THX setup rather than Dolby.

Thanks again!
Edited by shaneb0422 - 12/6/12 at 7:44pm

What do you mean by the CC being unique?
It would be exact match to my front CC.
I figured slightly as much about the rear channels being somewhat mono (i.e. 6.1 style).
Especially considering the fact that they are positioned so close together, and discerning the LR from behind that close together seems unlikely.

The speakers I have on the rear now that would move to front wide are the same exact speakers 2400LR - so they will fit. Interesting they get so much program - I am intrigued.

Right now I am looking at getting a couple older model year AT's on craigslist - this may free up some speakers depending on how they perform compared to what I have.

Do the Front Wide go at same same physical height as LRs? Or up higher?

EDIT_after some reading - it looks like I don't have room to do wides. Here is a pic -
I could do heights though.

Edited by shaneb0422 - 12/8/12 at 12:01pm