It looks like we have PCIe 2.0 which supports 500/500MB simultaneous read/write bandwidth. There are some cheap Asus 10Gbe adapters that could possible use all the bandwidth available (read from SATA, write to PCIe and in the opposite direction), so we can see close to 400/400 out of 10Gbe port without RAID overhead. I'm not interested in RAID, just a JBOD performance
Edit: Not sure about the exact wiring in Espressobin and capabilities of shared SERDES lanes among PCIe2.0 and SATA, some research says around 7.5Gbps total throughput, so I'll lower expectations to 3Gbe full duplex speeds with separte 10Gbe card in mPCI slot..
I believe @tkaiser could say a word or two on the matter