Currently, in a 7.1 set up, the sides are mounted horizontally.
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Sourced the Genelec 8000-442B Short Adjustable ceiling mount for this with the T plate adapter which allows you to mount the speaker horizontally.
Anticipating adding more I had them install 2 runs of 1" conduit up each side and across the cloud. 1 for cat 6 and 1 for AES.
But yeah to your point if I go 7.1.4 I guess the sides would need to be floor level. I need to speak to Dolby about this.