I'm considering buying myself a baking mat and need some CHer-input on which one works the best. Why is Silpat double the price of the others? Is it much better? What is the difference between having a silpat-style mat (fiberglass sandwiched between silicone) vs. plain silicone mat? I plan on using it mostly for baking cookies and bread but have also heard it works well for oven roasting potatoes, chicken, etc. Any thoughts?