@brianchoate differences: v2 requires docker, v3 has both: docker and deb native packaging
@brianchoate v2 has more documentation, but v3 is simpler to use. v2 has scan functionality, v3 doesn't have (yet). v3 is currently used in production by us, so it's going to be released as stable, just after documentation land.
so, well, it really depends on your case. probably the best is to try both and decide by yourself.