Outsource The Processing, Outsource The Profit
IT has moved from backroom accounting and reporting to operational systems in just about every line of business. Outsource your operations and you are left with a management shell that has to pay the vendor his profit from yours.
The usual argument is that the outsource vendor can perform the function more efficiently and less expensively. Which the vendor can only accomplish by paying their people less and having less reserve capacity.
Do you really want your mission critical functions being run less qualified staff on bare-bones systems? You don't, so you will end up amending your agreement over time in ways that drive your costs up to where they were before, plus paying the vendor his profit.
Not to mention, once you have committed to an outsource vendor, the cost of breaking that agreement and returning the function inhouse can be prohibitive. It is common in my experience for the first contract to be quite reasonable, and then for the new term contract to be high enough to recoup the vendor loss on the first contract and then some.
"Once you pay the Danegeld, you will never be rid of the Dane." Those considering outsourcing would be wise to consider what became of Ethelred The Unready; (poor Ethered, who took advice from his era's top management consultants).
The only time it makes any sense to outsource a function is if you regard the function as having no possibility of profit, and as a fixed cost of supporting the profitable part of your business.