Hiring a HAML/SASS developer can greatly enhance your web development process. They bring efficiency and readability to your code, reducing the complexity of HTML/CSS. With their skills, you can create cleaner, more maintainable, and DRY (Don't Repeat Yourself) code. SASS allows for the use of variables, nesting, and mixins, making CSS more dynamic and reusable. HAML provides a more elegant and simplistic syntax than HTML, improving productivity. These technologies together can streamline your project, reducing development time and potential for errors, thus improving overall quality.