I think that any AgCl/Br/I emulsion would probably give similar results unless there is an additional something in the way they added an overcoat, or a special support they used.
Chloro-Bromide papers such as Portriga tend to have better keeping properties when frozen than ordinary Bromide papers.
I'm not intending to move this thread off-topic but it stimulated a thought for a suggestion: I'd like to see a discussion thread about the basic types of B&W papers, ie, silver-chloride, bromide, chloro-bromide, ect. In all my readings (which are far from all-inclusive), I have never seen such a treatise and I've always been a little stumped when discussions on these basics get going.

Maybe I'll start the thread later today unless someone more informed wants to get it going.