First we rewrote echonests truescore logic in perl and then altered slightly and implemented some extra checks to further try to exclude false positives. We also believe what they used in the late song/identify API might have been different from what is open sourced in https://github.com/echonest/echoprint-server
Also we pack each individual hash before storing in Elasticsearch and gained at least 50% storage space this way.
Our Fingerprint data is quite different from theirs(unreliable ID3 tags, N versions of same track) which is why we needed some tweaks.
So far the matching is still far from perfect...
Whether we will open source the whole thing at some point we don't know yet.
Music used in compilations, ads, intros etc are typical usecases.
Mixtapes & livesets of course are also great. But when pitch/bpms have been altered more than 1-2% we currently get a lot of false positives. We are still working on finding a solution to this.