I get problems with access control, however, that prevent it from working.
Yes...given
access to * by dn="uid=slurp,ou=users,dc=xxxxxxxx,dc=xx" write access to * by * none
The problem is I cannot access the slave database with dn="uid=slurp,ou=users,dc=xxxxxxxx,dc=xx".
because you have no access for anonymous to auth to uid=slurp.
slave# ldapsearch -w xxxxxxx -D 'uid=slurp,ou=users,dc=xxxxxxxx,dc=xx' -b 'dc=xxxxxxxxx,dc=xx' -d 255
Debugging on the client isn't going to be too informative here. Try "slapd -d acl" perhaps.