Parallel start-up and direct cutover/conversion

You have developed a new system for an accounting firm and are getting ready to deploy it. After debating the cutover strategies, you have narrowed it down to two possible options – parallel start-up and direct cutover/conversion. Which one would you prefer and why?

Research these two cutover strategy options and present your preference in your initial post along with an evaluation of the pros and cons for your choice. Support your preference with both examples and research.