Here's an interesting tool to evaluate your sermon manuscript, if you do what is often referred to as "scripting" or writing the way that you speak. While my sermon never sounds exactly like my manuscript, I do write the way I speak. Writing for the ear and the eye are very different and thankfully no one is judging my grammar!
From that website: "Each sentence is highlighted by its length so you can see the rhythm of your prose — a wall of one colour is monotony; a healthy mix is music."
Simply paste your text and it will show you the rhythm of the writing. Whether in your writing or not, rhythm and variation of it in your preaching is important homiletical technique, in my opinion.