Access auth granularity?

[Dora Paula <deepee@gmx.net>]

Dear List,

I've two subtrees that contain user-accounts:
ou=usersA,dc=example,dc=com and ou=usersB,dc=example,dc=com.

Goal: Users below ou=userA,... should only be allowed to bind using 
sasl_bind, but not with simple_bind. Whereas users below ou=usersB,... 
should be allowed to bind using both (or any kind of bind).

I searched the documentation but without success. All I found was 
disallow simplebind and sasl_ssf, but both seem to make no sense in this 
case: While the first disallows simple_binds globally, the combination 
of sasl_ssf and access auth is or at least seems contradicting to me.

Question: Is it possible to achieve this goal using current openldap 
release?

Thank you very much

Dora