https://tools.ietf.org/html/draft-howard-rfc2307bis-02
They only thing that jumps at me is the name. It doesn't follow rfc norms. Normally a new standard would be rfc and then the next number available. This one deviated, It used the same number as the old one and appended text. The standard itself is good enough to be used by Active Directory and FreeIPA by default.
I am having a really hard time finding anyone who says that the standard is bad. I am willing to bet that if Luke Howard puts out this latest proposal out under the name of the next available rfc number today, which according to ftp://ftp.rfc-editor.org/in-notes/rfc-ref.txt would be rfc8203 it will be approved before the end of the year.
According to Ludo here https://ludopoitou.com/2011/04/20/linux-and-unix-ldap-clients-and-rfc2307-su... , I can campaign for the standard myself if I had permission from the authors.
I would do it to streamline documentation and, get the new standard into OpenLDAP 2.5 so it will be in OpenLDAP 2.6 by default.