[CHAT] Cotton or silk floss for Scarlet Letter sampler kit?

I am considering buying the Dora Sanger sampler from Scarlet Letter and not sure which to choose. I do consider this to be an heirloom project so I don’t mind shelling out the extra $45 for the silk floss, but I have never used silk floss for cross stitch so would welcome your thoughts on working with it, and how it would show in this particular piece. Many thanks!