Can't compare to doing XDP relationships over 10G, but I can share my experience running standard Snapmirror (DP) over long distance 10G (1000 mile replication, latency 24ms round trip).
My sources are two 4-node clusters - "small" (2x6240,2x6220) and "big" (2x6280, 2x6290) both replicating to a single 4 node (4x8060) cluster at the target. The "small" source cluster is mostly high capacity disks (3/4TB), the "big" source cluster is all performance disk (600/900GB). All replications are to capacity disk (4TB) at the destination end.
My prep test was to run volume moves internally on both source clusters. Volume move for all intents is an internal snapmirror (with obvious bonuses for keeping it live all the time). I used these tests to set expectations of how fast a snapmirror might function. At best my small cluster would go just under 1Gbps for volume moves and my big cluster would go closer to 1.5Gbps. These set the limits for a single replicaiton speed I'd expect.
For the replications, I maxed out the WAN receive buffers ahead of time (because of the low latency in the network):
network connections*> options buffer show
Service Layer 4 Protocol Network Receive Buffer Size (KB) Auto-Tune?
----------- ---------------- ------- ------------------------ ----------
ctlopcp TCP WAN 7168 true
ctlopcp TCP LAN 256 false
I've found that transfers from capacity disk are very much limited by disk speeds. I control all replications with scripts because the standard schedules don't work well enough to keep the pipe at maximum speed - replicating updates about 1800 volumes daily. For the small cluster, I limit current replications to 3 per aggregate, which seems to be as fast as the aggregate will go before disk limitations slow down individual transfers. The control script starts updates and monitors every 5 minutes to start up new replications in each aggregate. Even so - the best the "small" cluster has ever achieved is about 5.5Gbps over time, and individual transfers are always less than 1Gbps. Best I've ever seen on an individual transfer is about 700Mbps.
The large cluster just fires on usual schedules without regard for aggregates. Nodes don't seem to sneeze at it much - the large cluster can easily fill the 10G pipe with multiple transfers, though individual transfers max out near the 1.5Gbps mark similar to the internal move.
