Hi Ian, I think I made a similar point some years back. 65 will be 65 in all speakers in theory.

The only thing that might make the 8k sound effect the round different to, for example, a 5k is the low frequencies. They might flare up in the room and certainly placement will be important.

FWIW I found the 8k better behaved than the 55k. Side firing bass is better distributed.

Sitting away from the rear wall is sensible and I speculate that it is due to the height of the 8k tweeters and mid. these might more easily hit the wall above and behind the listener and reflect down to the listener. A 5k would possibly reflect up and away from the listeners ear or even be absorbed by the listener and sofa more.

Late at night I will listen in the quiet hours at 40-45 and if you had eyes shut you would never guess that the 8k was the size that it is.

Leading from that you might consider a smaller speaker if you plan to listen at low volumes. Larger speakers come into their own when you see just how capable at volume they can be.

Just my 2p

Rgds,
Nick