Hi Javier,
Thanks for taking the time to make this suggestion.

In the meantime, this could be achieved as a customisation on your installation to the /admin/templates/$templatename/clientsummary.tpl template with some conditional logic, something like:

{if in_array('Create Invoice', $admin_perms)}
**Code here for Client Stats**

The template contents containing the statistics is currently around lines 95 - 135.