Hi Nicola,
No, you should be fine here. This is the only restriction that I have seen for this;
User cannot be Authenticated / Unable to Connect to the LDAP Server
After the installation of the Active Directory plug-in for Cisco CallManager in a Multi Level Administration (MLA) environment, access to the administration pages fails with the You can not be authenticated successfully. Unable to connect to the LDAP server error message.
In a Cisco CallManager environment where MLA is enabled, if the Active Directory plug-in is installed, access to the administration pages is lost. You can observe this problem if MLA is installed before the Active Directory plug-in is installed. Install the Active Directory plug-in before the MLA installation.
Complete these steps in order to address this issue:
Uninstall MLA.
Refer to the Uninstalling Cisco CallManager Multilevel Administration Access section of the Cisco CallManager Multilevel Administration Access Guide.
Re-install the Active Directory plug-in.
Refer to Active Directory 2000 Plug-in Installation for Cisco CallManager.
Re-install MLA.
Refer to the Installing Cisco CallManager Multilevel Administration Access section of the Cisco CallManager Multilevel Administration Access Guide.
From this good doc;
Active Directory and Cisco CallManager Integration Troubleshooting Guide
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a00801d3c48.shtml#ldapsvr
This doc also has some good info;
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/4_1_3/ccmcfg/b07mla.html#wp1022546
Hope this helps!
Rob