I had great germination with rockwool and never had an issue with growth, damping off, moisture retention or fungus/mold problems.
What I liked most about it was its ability to retain moisture for a long time without harming the plants
I did soak the rockwool in water with a bit of vinegar though.
What I did not like about Rockwool and When I stopped Hydro, I was afraid to plant in soil with the rockwool intact, not sure if it would hurt the plants that and the fact I didn't want Rockwool in my soil, my gut instinct was to not use it in non-hydro gardening.
Its also not a very environmentally friendly product and has a high PH, as far as being a carcinogen, it hasn't been proven either to be safe or unsafe.