CM1's ALL AROUND?

Assuming you're getting the surround pair used and that you really like the sound you have so far, I think having largely the same speakers all around would outweigh any savings you'd achieve by buying cheaper surrounds. If you're not running a subwoofer maybe another option would be to pick up used CM7s and put your CM1s in the rear. Personally, if that's the situation I'd get the CM1s and add a good sub later. Best of luck.

Good advice. Are you looking for another set of CM1s rather than floorstanders due to a small room ?
If all CM1, you should have a subwoofer.

Yes I am in a semi-small room. Maybe 20 feet x 30 feet. Although I am portioning only half that as my living room but it opens to the kitchen and dining area.

I do have a sub-woofer JBL SP150. Not the best. Sorry forgot to say that.

The CM1's I am getting are new actually but last years model as they are priced almost 35-40% less.

Should I go bigger in the front and push the CM1's to the back? That might get costly!

Yes- Get floor standers for the mains speakers and you room acoustically is still large.

Take a look at this article, especially the last comment. All identical speakers is the absolute best for a multi-channel system, theater or audio. A sound may move through the room in anyway imaginable, or be fixed at any place in the room, therefore any two or more speakers may be used to create the sound.

Looking at the picture in Matching Front and Surround Speakers, it is obvious that the jet would sound exactly the same, front or rear in the room, with all identical speakers. Using a timbre matched system, like CM7 front and CM1 rear, should be extremely close, but still not exactly the same. One reason some use larger fronts is for also playing 2 channel audio only, but they are not necessary for multi-channel. That said, I would use CM1's front and rear, and look toward upgrading the subwoofer, as a better sub would definitely be beneficial in that size room.