I'm getting close to releasing another update for my UE FBX Tools addon, and created a new branch on GitHub with my current WIP version.
Lots of work went into the new UI to remove clutter and make the tool a bit more coherent, as well as some performance improvements for auto-generation and displaying normals as 3D lines. Most of the addon also works in Object Mode now and normals can now be applied to the mesh to alleviate most of the guesswork that came with my 3D lines display approach. The copy/paste functions have been replaced by a call to vrav's Transfer Vertex Normals addon (which is required to use this feature).
I've also updated and tweaked the old 6.1 exporter and added an exporter for the FBX 2013.3 (7.3) format based on it. The new 7.3 exporter currently doesn't support animations (something I want to finish before final release) but should export everything mesh-related. (Cameras, Lights and Null objects are also not exporting at the moment). The new exporter can be selected in the export menu by checking 'Use FBX 2013'.
Both exporters also have a new feature, 'Merge Vertex Colors'. Enabling this on export will combine your vertex color layers into one in the exported file, which is pretty useful when using vertex colors as inputs for wind or other effects that can be influenced by specific colors.
The new test release is available here (Github).