BPO - To offshore or not to offshore?

Many companies choose to use the 'captive' route, which sees a business send some of its back-office functions outside the company to a shared services centre - perhaps offshore, though not necessarily - yet they remain 'owned' by the customer. It's a form of BPO, but some argue that it falls short of all of the benefits of 'true' BPO, where a third party takes over the business processing.