I saw this recent post on the FMA:
As of May 31st, Spotify chose to shut down the Echo Nest Rosetta Stone, which was a product FMA used for years to power our search engine and similar artist recommendations. Rosetta Stone allowed FMA to psychoacoustically analyze our own tracks for abstract properties like mood and separate our library from the rest of the Echo Nest universe.
As of right now, the FMA search engine can no longer search by mood or tempo, and artist pages will no longer include a list of similar artists. However, we are currently working on major upgrades to the search engine, including an expanded set of filters, more sorting options, and a more complete keyword search. We are also looking into alternative third-party music metadata and acoustic fingerprinting services. […]
I already commented on their post, but I was wondering if (1) I am right in thinking this is the kind of services MetaBrainz (and more specifically AcousticBrainz) is capable of providing, and if (2) a MetaBrainz employee should contact them directly to discuss it.
Personally, I think FMA + MusicBrainz would be the most beautiful match ever made… 
And I dream of further MusicBrainz / FMA integration. (Related to this: FMA import script)