There are currently 2 forks of SFZero which provide useful new features.
https://github.com/schellingb/SFZero
https://github.com/jamiebullock/SFZero
Would be nice to get everything together in 1 repo, so we don't have to choose between features.
I would rather submit bugs against the forks, to request a PR from them, but they have closed the reporting of bugs :(