Using the 4.9x client, you can enable LDAP Contextless Login. I can list
the contexts I want searched and LDAP will search them (and their
sub-contexts) in the order they are listed. The return display, however,
is not alphabetically ordered. It lists the user accounts it finds in the
various sub-contexts, but in no apparent order (certainly not
alphabetically). Is there a way for the display to be alphabetical?

I've thought that I could list each search context individually, rather
than let it search sub-contexts, but that could have several drawbacks.
Would listing numerous individual contexts slow down the lookup, i.e.
listing 15 individual search contexts versus one container with the search
sub-containers option selected?

Catalog Services (which will be replaced by LDAP Contextless Login) orders
the return/display list alphabetically so it's easier to find the correct
user account/context.