Hi Reuben,
Thank you for replying. I see you're inquiring about X710 and not XL710 model - my mistake.
Yes, Cisco* Twinax cable would work with this adapter since it is compatible with SFF-8431.
Let me share with you the Intel® Ethernet Converged Network Adapters X710 Product Brief.
With regards to your inquiry on 1G Copper SFP+ modules, it is likely that it will work with this adapter. Since we do not manufacture 1G Copper modules, there are third party companies manufacturing these modules performs tests for compatibility with our adapter. Just like what we have for Intel® Ethernet Converged Network Adapter X520 Series. Please refer to the link below:
Which SFP+ Modules, SFP Modules, and Cables Can I Use with the X520 Series?
Hope this is helpful. Feel free to contact us again if you have further inquiries.
Sincerely,
Sandy