> Anyhow, it's about time I learned to properly plan my
> disklabel (especially since I can't find the old 'auto
> defaults for all' option ;-) I have a vague recollection
> that the root partition has to be within 1024 cylinders.
no it doesn't

only partition from where you boot kernel need that.
you can boot kernel from dos partition (dosboot.com)
when netbsd kernel is booted whole disk is accessible and there is no
limit