I purchased a circular 9'' pan from Lloydpans and hoped this silicone mat would be a fit. It turned out to be absolutely perfect, a great relief.
Initially I tried to bake chocolate chip cookies (Claire Saffitz recipe) with it, but as expected, the dough ended up spreading wafer-thin during the bake, and that was with a negligible amount of baking soda. Only one cookie out of 96 was sacrificed in this experiment, so no big deal. I've yet to try again with the baking soda completely omitted or baking at a higher temp, so it's possible the mat will still be okay to use with that particular recipe. I'll refrain from speculating and move on.
Next I tried baking brownies, and later on some buttermilk biscuits. This, also as expected, produced flawless results for both. The level of browning the biscuits used to have via direct contact with the pan was good, but it gave the bottoms a bit too firm a crisp for my liking, even though it does highlight the caramelization of the butter really well and I like that extra flavor. When using the mat, the browning was reduced just enough for the underside of the biscuits to have only a light crisp for the very outer layer, and as soon as your teeth sink past that layer, it's instantly supple and buttery in the best way. The mat slowing the browning process definitely leveled up the texture for me, and they're the best biscuits I've ever had in my life.
The brownies never had any problem with direct contact with the pan in terms of texture or flavor, but unmolding took a bit of care. With the mat though, the unmolding impresses me every single time, to say nothing of the time and water I save from no longer have bits of baked-on food stuck to the pan.
Overall, while I can't be sure how well silicone mats in general play with recipes that require specific rates of spread (certain cookies), it's a no-brainer upgrade for everything else I've tried. In fact, I don't even have to reach for the mat whenever I want to use it; I keep it stored inside my 9'' pan since it fits in there so perfectly. They've never been apart ever since -- perfect companions.