Does anyone have any hard core data or published reports on the ROI (return on investment) and TCO (total cost of ownership) of an multi-channel ecommerce suite from single vendor v/s integrated point solutions from multiple vendors?

I am referring to the following business functions:
  • Ecommerce Storefront
  • Content Management
  • Marketing
  • Merchandising
  • Order Management
  • Inventory Management
  • Fulfillment
  • Contact Center and CRM