We’ve been using Vagrant (Virtualbox) + NFS for years for Drupal development, and performance has been acceptable, so I imagine it would be fine here as well. It’s important to us that the volume doesn’t double the disk space required (which I believe docker-sync currently does).
For the Docker folks, here’s a sample Dockerfile illustrating the problem. These numbers are actual output I got on 1.12.2-beta28.
Finished stat x 1000. Local: 2ms, Mounted: 245ms (11156% difference)
Finished open x 1000. Local: 3ms, Mounted: 778ms (19496% difference)
Finished write x 1000. Local: 1ms, Mounted: 249ms (14827% difference)