Just found this thread, and thought you may be interested in the BoM tool I have been working on.
Source is available here: https://github.com/SchrodingersGat/KiBoM
Currently the CLI version is stable, I'm working on a GUI version which is not complete yet.
There are a number of features which I have found lacking in both the default BOM scripts and some others I have found online. If anyone likes what I've done, please feel free to contribute. I have designed this to be very user-configurable (although there is only a small number of options available currently).