http://www.monkey.org/openbsd/archive/misc/0408/msg00562.htm...
The TLDR from the OpenBSD side of things:
Hey, if ultra-precision time is an issue, go buy an atomic clock, I'm sure if your needs are that precise, you can probably afford it. openntpd is intended to be SMALL, SIMPLE and SECURE. Not HUGE, COMPLEX and "Hope for the Best".
http://www.monkey.org/openbsd/archive/misc/0408/msg00562.htm...
The TLDR from the OpenBSD side of things: