Thanks Watts and Rebecca for the comments.
In my opinion, diamond cut alloys have great showroom appeal, but can be a bit fragile, and more expensive to refurb than powder coated wheels. In spite of me looking after mine really carefully on my mk6 GTD; regular washing, sealing and waxing, and touching in any stonechip damage with clear lacquer, two of my diamond cut alloys still succumbed to whiteworm corrosion.
Ditching the diamond cut alloys also gave me an excuse for ditching the Bridgestones too!