Is it a must to keep kernel up-to-date for -current pkgsrc user?

[Mayuresh <mayuresh%acm.org@localhost>]

This document suggests if the -current code uses new system calls
supported only by newer kernel there could be a problem. So better to
update the kernel in such cases.
http://www.netbsd.org/docs/current/

I like to keep -current relatively more frequently up-to-date than the
kernel. So it's not obvious when to update the kernel.

Is there anything in pkgsrc that will warn of need of a kernel upgrade, in
case the changes use a new system call?

Also, once you are using pkgsrc -current and take care of above issue with
kernel update, an "upgrade" (i.e. downloading an iso running sysinstall
etc) is never required. Is it?

Mayuresh.