Blu-ray audio confusion

It is not clear whether modern audio receivers that are certified
for blu-ray can handle both the standard dvd 6.1 (channel behind the
listener), and 7.1 (2 channels part way between front
and back speakers).

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Some receivers are labelled as
both.
Should we assume that we can attach cable for
both systems, or must we cable for one exclusively?
A few blu-ray disks actually for hd audio use a lossy
stream with Dolby ex (6.1)

We need guidance

Blu-ray not needed

Much of what the Blu-ray system offers I get
with standard dvd. The bonus view
pip feature is already on several regular disks:
Glory, Jerry Maguire, Planet of the Apes (remake) etc.
The Ultrabit line of disks offers an image on
anything under 40" that impresses. I have about a dozen
concert disks that carry 24/48 pcm stereo (which Prologic
spreads to my surround speakers. A handful of my music disks give
24/96 pcm stereo and full motion video.
The exception proves the rule
If disk producers did not fully use standard disk
features, why should we support the same features
as an excuse for new equipment purchases?