BWF is also a good master format:
It's WAV compatible, but with a standardised metadata format:
To be truly 'pro' we should support BWF in Airtime, and therefore WAV as a subset of BWF. This guy has commented on preserving BWF metadata in the conversion to/from FLAC:
This requires the use of the --keep-foreign-metadata option when encoding/decoding:
If we can verify that works 100%, then we can support BWF indirectly by supporting FLAC. On the other hand, there may be stations that don't use a remote workflow, and would prefer to buy more storage than use FLAC compression, just to take one step out of the editorial workflow (e.g. if they have standardised on an editor tool which supports BWF but not FLAC directly).
My personal feeling is that if they don't have a remote workflow now, they might in future, once they consider the possibilities. So FLAC will be the working exchange format of choice, because we can never have enough bandwidth.