Mike, this aluminium oxide based paste is even thicker than copper grease,
even more high temperature resistant and prevents electrolytic corrosion
of brake and suspension components.
VW recommends only to use this kind of grease (like VW's own 'Optimol').
Fwik Porsche was the first company that has given a similar recommendation.
And yes, the S3 alloy hubs are much 'bulkier' than the steel hubs. So longer
bolts and a different shaped mounting bracket are required.