stay as a -devel until it's formally released, which should be soon'ish.
BIND 9.9 includes a number of changes from BIND 9.8 and earlier releases,
including:
NXDOMAIN redirection
Improved startup and reconfiguration time, especially with large
numbers of authoritative zones
New "inline-signing" option, allows named to sign zones completely
transparently, including static zones
Many other new features, especially for DNSSEC
See the CHANGES file for more information on features.
https://kb.isc.org/article/AA-00592
