Thanks for the replies to my question.
Another factor making me go towards the SCS 8 for surrounds and ceiling over the 7 Series is price. Eight SCS 8 speakers are whole lot cheaper than eight 7 Series speakers. If there is not too much sound quality variation between M2 as LCR and SCS 8 as surrounds/ceiling, I will quite surely go with them. I was told that after some EQ/room correction work, the setup will work very well. Even JBL used M2 as LCR and SCS 8 as all surround and ceiling speakers during the 2014 or 2015 CEDIA demo.
One more question...
If, and only if, I decide to go with Klipsch speakers for my new home theater (the upcoming RF-7 III for front left/right, RC-64 III for center, and RP-160M for side and back surrounds), could I use the SCS 8 as ceiling speakers for Atmos/DTS:X? I am asking because Klipsch does not make ceiling mountable speakers and they only have in-ceiling speakers which will not work for me as I have a concrete ceiling. Will the SCS 8 match the Klipsch speakers well enough for ceiling speaker duties?