Huh, must have I missed the change here, I thought it would all still be Rostygold.

I suppose that if you're using the Rat Market to fund a Scrip grind, you should always leave a certain amount unspent. Getting up to 20 Scrip directly definitely helps, assuming you'd just sell the Rostygold into Echoes for Brass Lollipops anyways. All the currencies can either be sold for Echoes as normal, or converted back into Rat Market sellables (Justificande Coins into Night-Whispers in Irem).