When using custom attributes for profiles, I would like the ability to have a globally defined default value for a custom attribute. This would be overridden by a group-level custom attribute (if specified), otherwise it would inherit from the global value. Finally, if the value could be overridden at the device level should that level of granularity be required.

So the order of precedence (from lowest to highest) would be:
• Global
• Group
• Device

A use case of this is for password policies. I can create a custom password policy with a custom attribute like {{requiredlength}} to specify the number of digits required for the password. By default, I want this to be 6 characters globally, but our execs only want to have to type 4. However, we have one exec that should have an 8 digit code. Using this model we would specify:
{{requiredlength}} @ Global: 6
{{requiredlength}} @ Exec Group: 4
{{requiredlength}} @ "Mr. Sensitive Exec" device: 8

This could be a really powerful way to reduce the need to create different groups for minor variations in policy, keeping group management ... erm ... simple