HA HA HA....lots of people disagree with Rainbow and I'm the first to admit it.
As far as I know, Solid Gold didn't "refuse to release" information about ingredient changes. They had "by law" six months to change their bag information. When they were emailed/phoned about the change they were upfront about it.
As far as the cranberry studies, I've never had any reason to look into it, but there is probably enough info out there to find a safe dosage.