It looks like the Intel 800-series NICs can split 100G ports into 4x25 and (potentially) 8x10 using their 'epct' tool, but it's unclear if they'll support 25G and 10G links on the same physical NIC at the same time. Their docs show 4x25, 2x2x25, and 8x10 as options, but there's no mention that I can see of (say) 2x25 + 4x10 or connecting a 10G device to a 25G port. It looks like this could solve some of my problems, but only if I can mix 10 and 25G links.