I also found 7.0 to be better than 5.0 in my room.

It was a lot of DSP in a modest room though.

I am now 2.0.

The room the OP describes should handle 7.0 very well. Lots of choices for the surrounds depending on space, walls, furniture etc.

8kSE will be a stunning front though so to be honest I would care to much about the surround for music. Movies ok.

Rgds,
Nick