Just had the panel driver update.
The engineer came out with 2 SD cards, one with the PEAKS update (which I already had) and one with the panel driver update (which I didn't).
The screen cuts out during the panel driver update, which makes sense. I can also see why Panasonic wouldn't want an end user to perform the update. The temptation to reset the TV after the screen goes blank...
Has it worked? I had a mild case of the problem in the centre of the panel. I can't see any difference yet, but will keep an eye on it.
One thing I will say is that flicking between my calibrated mode and the THX preset, the green splats are much more obvious pre-calibration. Calibrating does improve it, at least in my case. There is still what looks like static noise in the middle of the screen after Greyscale calibration, but it's much more distinct prior to calibration.
Let's see if this improves with time...