One thought on selecting copper cookware - get copper with a Stainless Steel interior rather than Tin.
1. Tin melts at a low temperature of only 450-F, Stainless Steel at 2,782-F
2. SS is much harder than Tin - Tin is rather like the old Teflon coatings - scratches and is worn away easily exposing the copper to the food - and the tin that is worn away goes into your food.
3. Tin linings have to be re-tinned from time to time (see #2 above). This increases the cost over time - and finding someone who can do it is getting harder all the time.
4. With the copper exterior doing the majority of the heat conduction - I doubt you'll really notice the minute difference in the conduction thru the SS vs Tin lining.
Yes - I know that the old "Classic" French copper cookware was tin lined. Tin was discovered as far back as 2870 BC (in the Bronze Age) - Stainless Steel wasn't "discovered" until the 1920's.