I have heared in the past demonstrations of 2+2+2 on DVD-A
That is very good with a recording made for it.

We even have support for that with Meridian processors, and the catalogue is only 50 titles perhaps.

Artificially created height from Prologix 2x is perhaps less good, but i never had a good demonstration of that.

Also i do not think you can compare it with going from 5.1 to 7.1, but from 2.0 to 5.1, it adds a dimension.

Sold all M equipment