Bob still drives the v3.x releases, has a few words about the release candidate. The focus for this release was Visual Studio 2015 support. Whether you have VS2015 or not, I encourage you to download this release candidate and try it out. If something that used to work no longer works, please file a bug
Random interesting fact. The first WiX v3.9 RC was a year ago minus two weeks ago. I guess that makes sense since we timed this release to coincide with the Visual Studio 2015 release which was expected to release about a year after 2013. So here we are.
In the meantime, keep coding. You know I am.