Ever wondered what the real value is in granting this mode to a User? 

This allows you to setup a User in CRM, who has ‘Restricted Access’ to the application; but they can access the ‘Settings’ and ‘Customisation’ area of the application – providing that the security role you assign them permits access to these areas of the application. This can be useful for Users who need to do configuration and/or customisation but not actually utilise the application.

The benefit of this mode is that any user who has this mode set does NOT consume a CRM license.

One other benefit of this Restricted Access Mode is in the area of ‘Service Scheduling’.  Ever have to schedule third party resources? (I.e. Sub Contractors) and you don’t really want to have to grant every one of them a CRM license (as they most probably will never log into the application).  Then set them up as CRM Users with Restricted Access Mode and you can now factor them into your service scheduling rules.  Of course you will have to work out how to notify the subcontractor where and when they are scheduled – but that could simply be an email notification to them.