When I saw the results I did not believe, so I reviewed the benchmark code. It is basically the same SQL commands being run in normal SQLite and with the branching enabled.

Yes, LMDB is proved to be safe. It is used in many apps and even other DB implementations, including Monero.

What I have not tested is SQLite with WAL (Write-Ahead Log). In this case it may be faster than the default journal mode.