Ethernet is quite a bit more costly for 10G. In our deployment we use SFP+ with 3m DACs which are downright cheap, plus long fiber runs which are more feasible

Ethernet is quite a bit more costly for 10G. In our deployment we use SFP+ with 3m DACs which are downright cheap, plus long fiber runs which are more feasible and less expensive for connecting sub-sites. We support 10G-BaseT as well for devices that are 10G-PoE-BaseT but otherwise standard here is SFP+. Gets even cheaper when you consider power consumption, heat dissipation, and multi-port cards (2xSFP+ NICs are extremely affordable and nice when you have segregated networks or VM hosts). EDIT: 10G-BaseT also has ~2 orders of magnitude higher latency compared to SFP+ Fiber, and ~1 order of magnitude higher latency than SFP+ DAC. The numbers are small across the board, but it's relevant. 5-10W draw for 10GbE compared to 1-2W draw for SFP+ Fiber, for power consumption numbers.