Bob, Dolby collaborated with Jim Fosgate in order to expand PLII to PLIIx. At the time PLII first came out, Fosgate had mentioned publicly that PLII (like any matrix decoder) was capable of going past 5.1. While adding rear vs side vectoring to the surrounds, Fosgate also made a couple of further refinements.

The first tweak involved a very subtle change to the Centre Width steering control, which may or may not be noticeable to most users. The other change should be more audible. PLII Music mode has a mild shelf filter applied to the surrounds to make them sound a little more subtle than the PLII movie mode (which doesn't roll off the surrounds). Some listeners had complained that this caused the surrounds to appear comparitively dull in Music mode. So now when you're in the PLII Music mode, engaging the Panorama parameter will turn off the roll-off filter. This should make the surrounds appear a bit more detailed and aggressive, which goes hand in hand with the function of the Panorama adjustment.

Since Jim Fosgate was making these refinements anyway, for his all-analogue tube-based processor (which I think is due out late this year or early next year), Dolby asked him to add them to PLII. So, if the Outlaw 950 is upgraded to PLIIx, then its standard PLII modes will also be updated to reflect Fosgate's changes; subtle though they may be.

Best,
Sanjay