According to dev.yabbforum.com they will release YaBB 3.0 on April 1st 2010. I don't know if it's a joke 
YaBB 3.0 will finally come with mysql support and there should also be a converter.
In the meantime I think I can live with the current forum, since it's speedy now. The quirks may be fixed with the upcoming update to 2.4 I hope.