digest only peering?

Is anyone out there running their cache with some siblings (which they don't
control) peering only via cache-digests (ie, no ICP queries?)

If so, any thoughts on how successful this is? I'm considering trying this
with some other sites, if practical -- I don't really want to take on any
more ICP peers for simple reasons of volume of ICP traffic, but cache
digests seem a relatively inexpensive method of adding more peers into a set
of caches (albeit at the cost of memory, which isn't a problem on my cache
system at the moment).

Cheers,

Chris

-- 
Chris Tilbury, UNIX Systems Administrator, IT Services, University of Warwick
EMAIL: cudch+s@csv.warwick.ac.uk PHONE: +44 1203 523365(V)/+44 1203 523267(F)
                            URL: http://www.warwick.ac.uk/staff/Chris.Tilbury