[exim] dbm vs net-iplsearch for mixed ip/range lists?

hi all,

i'm migrating my exim.conf from lsearch to 'dbm' lookups.

i've read abt, and easily converted most of my list lookups.

i've an additional list, 'ipnets.blacklist', containing a *MIX* of ip
addresses, masked ip ranges, and comments, e.g.:

    W.X.Y.Z/16      # AOL Dynamic DialUps
    A.A.A.128       # mother in law
    A.B.C.D/20      # the government

with prior help from this list, i use it successfully with net-iplsearch to
drop on connect from these addresses/ranges:

    hostlist     blacklist_ipnets  = net-iplsearch;LISTS/ipnets.blacklist

    acl_check_connect:
        ...
        drop     message           = BLACKLISTED
                 hosts             = +blacklist_ipnets
        ...

but, i've not (yet) found an example of dbm usage for mixed-type lists, as
above.

i suppose a two-pass lookup string approach, matching 1st for address, then
range, is doable, but at that point is it simpler/faster just to do the
net-iplsearch on the text list?

bottom/line, is dbm lookup appropriate/efficient for such mixed lists?

any example/reference would be appreciated ....

thx,

richard