I know Modern D, and the even newer Ivory III D are all the rage these days, but it seems that quite without anyone really noticing, the Galaxy II piano's have become the Galaxy III piano's. In the process, the Galaxy II Steinway was dropped, and replaced by the Vintage D (which originally was a stand-alone VI).
There is pricing for the full package, and for two different types of upgrades, one of which is called "update", and the other one called "upgrade". I don't as yet know what the difference is specifically.
Also, it is apparently now possible for owners of the original Galaxy II Steinway to crossgrade to the Vintage D.
As an owner of the Galaxy II piano's I will have to think about this (even though Steinway D's are not my favourite by any means).
But whether there is any difference to the individual VI's themselves, in going from Galaxy II to Galaxy III, I don't know.