binary upgrade of a remote box

[Victor Sudakov]

Colleagues,

I have some remote boxes running outdated versions of FreeBSD like
8.2-RELEASE-p6 or even 7.4-RELEASE-p5

What's the least painful way of updating those systems to something
like RELENG_9_2 ? 

I am comfortable with the "make world" method and have done this
remotely before, but those boxes are too weak to compile their own
world, and the disks are too small. Mounting /usr/{src,obj} from a
remote host is not an option because of relatively slow and unreliable
WAN links.

I am very uncomfortable with "freebsd-update upgrade", at least it's
not something I would risk remotely.

Any more ideas of a way to perform a smooth binary upgrade?

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov at sibptus.tomsk.ru