Welcome to the forum. :flower:
It should be safe to assume that the MID is the same as their existing 6x BD-R discs (MEIRA1-001), which have been around for some time. Introducing a new code would be madness as no existing drives would support it without a firmware update.
Version 1.3 on the packaging refers to the Blu-Ray disc specification, not the blank discs themselves.
I expect that all Panasonic have done is redesign the label. I would expect the discs to be the same MEIRA1 as before. Hopefully the quality will continue to be excellent.
We have a thread here where members have posted their Panasonic BD-R SL scans.