Righto, today I put my homegrown starter head-to-head with Ischia. The Ischia has been active for a few weeks and seems stable. All using the same formula:
240g 5Stagioni: 63% hydration, 1.6% starter, 2.75% salt. 44hr ferment: 24 bulk, 20 balled.
Verdict - the Ischia is basically better, with a lighter crumb and subtler taste. Comparatively my starter produced a denser moister crumb and was noticeably more sour. The Ischia dough was actually different to handle, it was easier to open.
[UPDATE] the wife confirms in a blind test: Ischia is definitely the winner.