Copper SFP+ are becoming available, and _should_ work on x670-G2. But, as Drew pointed out, they use higher power than MSA Type-II transceivers. So, that means:
- you can't fully populate a switch with it
- you may have to insert them in a "V" fashion
- you will be limited in distance to ~30m on Cat6a
Now, from the original question, we do have switches with native 10G copper:
- x620 (10 or 16 ports models)
- x670V-48t (48 ports)
- 7100 (24 ports)