My two cents:
I made two batches. The first I cooked to a temp of 242 and it was just too soft for me. The second batch I cooked to 250 and it was delightfully firm, but still easy to cut and bite into. Still soft, but had an al dente tooth feel that I love! Also, I only had salted butter. I just covered the bowl with a plate while I melted the butter, and it does splatter up. But once all the ingredients were combined there was absolutely no splattering. I also lined my pan with parchment paper. Pro tip: Never put wax paper anywhere near caramel. Even if it has cooled, wax paper is just too finicky for caramel. Wrap your pieces in parchment or even better, cellophane wrappers, which I prefer. They look professional.