They don't have BPA, that's the marketing and it is true. But that doesn't mean that other estrogenic chemicals are not leaching, or that the non-estrogenic chemicals that leach are safe to ingest everyday for a lifetime.
Right, the rubber gasket worries me with the boiling water. I also had to stop using sous vide machine because silicone bags leech chemicals above a certain temp. I was mortified when my friends mentioned they use ziploc bags in the Sous vide baths.