I'm not sure what the discussion is here: how we feel about the possible banning of lead bullets, or the performance of copper bullets, so I'll answer both. For my part, I don't have a problem with banning lead. In any form, it's pretty detrimental to the environment... as well as humans.
As for performance, I have used the Hornady GMX (which is not made of pure copper, but gilding metal which is a little harder) and the Barnes TSX and TTSX - very close to the TMX functionally. All these bullets have been very accurate in all my rifles (as accurate as lead, for sure) and the TTSX has been very bad news for a couple of nice Montana bucks. Everyone that I know who has used copper like it. It's not mandatory here, but they still are isung it.