I have a few repositories running on Berkley DB for a few years now.
Never had a single problem.
Some are running on very small Linux machines with very little memory
and old processor and BDB was never an issue. But then again, the only
time this machine went down was when the power-supply died. Other that
that it's always up, so never caused any problem with the DB.
In the past hot backup was only part of BDB IIRC. But it's now
available to FSFS as well, so not an advantage anymore.
I think both are stable enough to trust your code to, so it's a matter
of what's more comfortable.