Another thing the consumers can consult is guidelines made for museum conservators. They consider RA-4 type prints "unstable" and the guideline recommends limited brightness of viewing light during display, and humidity-controlled refrigeration during storage. B&W materials are quite a bit more durable than dye-based color images, although some manufacturers (I won't say who, since Ron will go on forever if I do---maybe he will anyway, even if I don't) have better dyes and dye couplers than others. There are several books written on this topic, and there are at least a few if you count English language only. They are written for museum conservators, conservation scientists and technical staff so they are more accessible than papers published on journals, though you often need to consult the latter for more details.
About the permanence of eastern/central european RC stock, I don't think anyone knowledgeable ion the subject makes a serious comment. RC paper production had several technical pitfalls that Kodak, AGFA, Fujifilm and Ilford got stuck several times. All of the problems are documented in various places, and you know what they are even if you are not an industrial spy. But figuring out how to iron out all the problems is not that easy... I'd definitely stick with products from above 4 until someone does thorough testing on others' products... but I am not hopeful that anyone will do such a task in this market situation.