Currently, if CRM is not in use, there doesn't appear to be an easy way to view a customer's sales order history from the customer screen. Invoices can be viewed via Inquiries/Customer Details, but these lack shipment information, and include payment and other data we may not want a user to see. Workaround here may be adding a GI under Inquiries, but a tab would provide easier navigation.
If CRM is in use, Actions / View Business Account leads you to an Orders tab. This spurs users to ask, "if I can see this on the Business Account, why can't I see this directly from the customer screen?"
Suggestion: In all cases (CRM in use or not), provide out of the box navigation from customer screen directly to list of sales orders. Ideally a tab like we see on the CRM/Business Account screen.