When is BuildWorld necessary?

[pobox at verysmall.org]

pauls at utdallas.edu wrote:
> No one has mentioned the security/freebsd-update port.  With that you 
> can apply updates to the kernel and world without having to build them 
> *if* (and only if!) you are running a GENERIC kernel.  For remote 
> administration, this may be a good option for some.

I read that this can be used _only_ nothing has been re-compiled 
locally, of have I missed something?

We have custom kernel due to database needed optimizations.

Iv.