For those of us that have tried CiviReport with ACL's and custom data, we'll be aware of the issue that in order to use the custom data in reports the user must have Access All Custom Data privilege enabled. This is not the desired functionality and thanks to funding from Leukaemia & Lymphoma Research a patch is available which cures the problem, allowing you to use ACL's with Custom data without compromising the CiviReport functionality.
You can get the patch from the following JIRA issue
http://issues.civicrm.org/jira/browse/CRM-11962
Parvez
www.vedaconsulting.co.uk