My experience has been that the SF has a more sour taste than Ischia but it is not a significantly sour taste when used in small percentages in dough. It also, at least withy he one I have revitalized from sourdough.com, has significantly more lifting power and seems to provide a more creamy quality to the crust than Ischia. I stopped using Ischia as my primary largely because it's more predictable than my other three starters. I tried a home grown starter, Camaldoli, Ischia, and SF in that order, and FWIW, would rank them in reverse of that order in preference. One thing that I noticed, which other members have frequently remarked, the Ischia starter gets a very strong cheese (or vomit) smell while activating, and when the feeding schedule is coming back up. Of all 4 starters, it's the only one that has this quality. It does go away once it's healthy and active. What are you looking to get from a starter? It will be interesting to hear what others report.