10-30 uSec make no difference in real-life cases because of the end-to-end latency of All-Flash storage on the guest level is 0,5-5ms on average. Also just deviation of latency of fast enterprise NVMe SSD (not mean, but 95-99th percentile) ~ 10s-100s us. 

More than that - there were public benchmarks of vSAN on RDMA and TCP/IP a few years ago that doesn't show a huge difference - http://www.yellow-bricks.com/2018/09/05/hci2476bu-tech-preview-rdma-and-next-gen-storage-tech-for-vs...