non-BDB support for DLZ in Bind9?

[PGNd]

In DLZ, as packaged with bind9, currently a variety of db drivers are supported,

    grep "AC_ARG_WITH(dlz_" contrib/dlz/config.dlz.in
        AC_ARG_WITH(dlz_postgres,
        AC_ARG_WITH(dlz_mysql,
        AC_ARG_WITH(dlz_bdb,
        AC_ARG_WITH(dlz_filesystem,
        AC_ARG_WITH(dlz_ldap,
        AC_ARG_WITH(dlz_odbc,
        AC_ARG_WITH(dlz_stub,

Of those, as (historically) pointed out @

    http://bind-dlz.sourceforge.net/driver_docs.html

BDB drivers provide the "best performance"

        Berkeley DB Drivers
            Currently two BDB drivers are provided with DLZ. In the future a third may be developed to provide even better performance. All the drivers take advantage of Berkeley DB's built-in caching to improve performance. The Berkeley DB drivers provide the best performance for DLZ. 

(1) is that still/currently the case with bind 9.10+ ?
(2) are there any available metrics comparing BDB with Filesystem drivers?

With BDB's licensing change from Sleepycat -> AGPL (cref: https://lwn.net/Articles/557820/, https://developers.slashdot.org/story/13/07/05/1647215/oracle-quietly-switches-berkeleydb-to-agpl) distros (e.g. Debian) & other server apps (e.g., Postfix) have added support for, and/or currently recommend use of, OpenLDAP 'LMDB' (e.g., http://symas.com/mdb/, https://en.wikipedia.org/wiki/Lightning_Memory-Mapped_Database), database as a license-friendly, performant alternative.

TBH, I don't know WTF is going on *currentlY* with libdb vX.X's licensing; it's all bit fuzzy so far as I've (re)read.  My personal preference is an Oracle-free deployment; opinions & needs vary, of course.

What's Bind's position on BDB dependency & support, and implementation any alternative such as LMDB, going forward?