I have committed a fix upstream for the SASL concurrency issue I found.
http://www.openldap.org/devel/gitweb.cgi?p=openldap.git;a=patch;h=431c4af526b18abb4a18c2c4c8655690b753cbe5Since I still don't know for sure whether it's the same problem you were having, it would still be great if you could try to test it at some point. Otherwise I may just close this bug when the fix reaches Debian, and let you reopen if it happens again.
