I may be wrong but I suspect the spring and damper rates that were developed for the heavier Aero 8 , have just been carried over onto the lighter +8 .
Therefore it will "bounce" more than the Aero 8 does, nothing that a bit of development with changing springs and dampers cannot cure, but perhaps annoying that it is not optimised.
You will be pleased to hear that the springs and shockers are optimised for the Plus 8 Andy, as it is over 100 kgs lighter than the equivalent Aero 8 and thus the poundage of the springs is completely different.
On a separate topic Corsu, the chassis of the Aero and the Plus 8 is the same apart from at the rear, where the Plus 8 chassis is similar to the Series I Aero whose boot was formed in wood, rather than later iterations where the boot supports were aluminum formed. Both the new Aero and the Plus 8 benefit from the new steering based on BMW parts, which I and others, think is a big improvement.