The FHS-10 is an excellent blade, not better or worse than the GEM SS PTFE blade. Definitely not worth the extra cost to use in a GEM razor.
I have a Valet VC4 coming that I will use the FHS-10 blade with.
I hope you have better luck with the VC4 than I did. It was the last of the AutoStrops produced by Gillette. By that time, Gaisman had retired and there was likely little love for the Valet division.