FWIW, I've found that all my prints made on Foma VC RC paper and stuffed in cheap frames (the sort you can get for $5 at CVS or Walgreens) silver out within 1-2 years. I've used various fixers, but mostly TF-3. Prints made and framed in exactly the same way on Agfa VC RC paper haven't silvered out on me, even after ~5 years. (That's as long as I've been doing B&W printing, so I have no longer-term tests.) Prints made on the Foma paper and stored loose in envelopes or boxes haven't silvered out on me; just the framed prints have done so.
All that said, I'm the only person I've seen who's reported this Foma-specific problem on APUG, so it's entirely possible the problem is an interaction of the Foma material with something specific to me -- chemicals in my wash water, peculiarities of (perhaps improper) processing on my part, trace chemicals in the air in my house, etc. If you're willing to wait 2 years for the silvered-out effect, though, and if you're willing to live with the probability that it will get worse and worse after that, you could try the Foma materials and see what happens....