Output quality immediately comes to mind, of course.

Models are converging, but they converge in bands, and frontier is frontier. I would not like to have any workflows in any area of my business where output is generated by an assortment of models from different providers. For trivial, mundane tasks that might be fine, but it certainly doesn't apply across the board.

How do you know they're following requirements ? At least a quick search about the company providing the service would be useful