MIL wants to purchase all her DIL's an All Clad Roti Pan. I told her that I thought they had made a few changes to their pans and that all the new ones now do not have an aluminum core but are just SS and warp on the stove top. The bottoms also are not flat but have ridges in them. Is this true? How can she obtain the old favorite I know and love? Mine has a flat SS rack but she was looking at the NS racks. I told her to stay away from the NS Roti Pans. What do you think she should do?