Correctness of operation does not only refer to end-to-end data integrity, but also to adequate capability to diagnose and inspect system state, in addition to being able to deliver correct output in face of severe software or hardware failures. Linux is out as far as all of those.
In other words, if you want JustWorks(SM), rock solid substrate for (web)applications, anybody not running on FreeBSD, OpenBSD, or some illumos derivative like SmartOS is out, at least for me. Perhaps your deployment is different, but I don't want to have to wake up in the middle of the night. I want for the OS to continue working correctly even if hardware underneath is busted, so I can deal with it on my own schedule, and not that of managers'.