I just bought Pierre Herme's Dessert book. He prefers to use cake and pastry rings on sheet pans lined with parchment rather than cake pans and tart pans. With the rings, he uses sheet pans so he can just slide the finished product off rather than having to lift a delicate cake or tart. I don't mind buying new rings because I'd like to try a more professional technique but can I just use an inverted jellyroll pan rather than having to buy new sheet pans as well. Is there any problem with warping of the pan as it heats and thus ruining the finished product?