....
This is a complete shot in the dark - Could it be that the beefed-up Neuspeed drop links transferred more stresses on the hollow ARB's? The VW oem droplinks possibly have more flex in them.
As I say, this is complete guesswork and anyway I would have expected Neuspeed to have thoroughly tested their combination.
Rightly or wrongly I now have much less confidence in Neuspeed's products and am glad I went for OZ instead of Neuspeed lightweight wheels.
In your shoes, Mat, I'd do exactly the same and take the opportunity to go for VWR ARB's.