I'm having a look at using espeak-ng instead of espeak in Debian, but I
couldn't find a release for it. Is the last version in git supposed to
stable? We don't usually take a random git snapshot of packages :)
The headers and voice data have been moved to avoid file conflicts with the espeak upstream versions (allowing both espeak and espeak-ng to be installed on a system).
eSpeak NG is still ABI and API compatible with eSpeak, and can read the eSpeak voice data.
NOTE: The voice data is now buildable from the command line without the wxWidgets dependency. This is all done in an autotools-based build system. Editing the voice data (i.e. an espeakedit GUI equivalent) is not currently supported, so the espeak version of espeakedit would be needed in that case.