Go with regular try-ply All-Clad. Demeyere is exorbitantly expensive for negligible difference in performance, and I don't agree with all their design choices, e.g. disk bottoms on certain pans. There's no reason to buy copper core over aluminum core, as the superior performance of copper is negated by the thinness of its layer and by being sandwiched between stainless. If you want copper, get it unclad. All of my saucepans are tinned copper. As for the D5, I do see a difference in evenness of heat distribution, but at the expense of responsiveness. Since I find my tri-ply pieces to be adequately even, and I value responsiveness over slightly more even heat, I see no reason to spend extra on D5. However, if evenness is more important to you, you may choose differently.