I can't see myself using it for serious production stuff.
Maybe it's not fair, maybe if I had spent as much time on it as I've spent on Linux, FreeBSD, OpenBSD... I could be a little bit more confident about it.
For example, I'm not confident about security work. I know, the less mainstream, the less botnets targeting it... but I'm not worried about botnets mainly.
Even for a minimal system, as the title say, I'm more confident building it in one of the operative systems that I'm more familiar with.
Still, I think that (Free|Net|Open)BSD, are something every systems engineer, should use and learn, at least for one year, at least once in life (if it's more, much better). It's like learning programming language B, even if everyday you use programming language A... It's like traveling... It is enriching and opens your mind.