Here's the progress so far on E's silk-cotton beret: I've finished the top and sides and I've just started decreasing to form the underside. I've just joined in the second skein of yarn, so now I know I'm going to have enough. I'm surprised and pleased with how firm the fabric is turning out. I did choose a crochet hook on the small side for the yarn because I wanted a stiff fabric, but the yarn isn't tightly twisted, so I didn't know how it would go. It's better than I expected.
Experimenting is always fun, but they always recommend sampling when using a new yarn. Oh well, what they don't know won't hurt them. I usually end up experimenting (sampling, if you like) on something that can be used. And I'm happy enough to change my plans to suit the way a particular fibre wants to behave. In this case it's behaving beautifully.