Nick,
Sorry for the delays in delivery of your speakers.
As you noted, the surrounds in cinemas are indeed quite elevated. You can experiment with the QS8 height if you want using a couple of stepladders (or able assistants) to temporarily position them while you do some listening.
The QS8s are very forgiving, and needn't be at identical heights or exactly opposite each other. One of mine is about 7 feet off the floor and the other about 5 feet. I usually advise customers to put them "anywhere from 2 ft to 6 ft above ear level when you're seated".
Be sure there is room for the banana plugs at the Yamaha's output connectors. Sometimes they are very close together.
Regards,
