What useful metrics a ‘Fitbit for Speech’ would have for people who stutter?

What useful metrics a ‘Fitbit for Speech’ would have for people who stutter? A fitness tracker (such as Fitbit) measures the distance you walk, run, swim or cycle, as well as the number of calories you burn. It also monitors your heart rate and sleep quality. As a person who stutters, I know how important it is to have objective data when I reflect on what I have achieved so far with my speech, to keep me motivated and to keep practising (I am usually too subjective with the way I handle speaking situations). For this reason, I decided to build a wearable speech tracker (BeneTalk.com) and I am very keen to know your thoughts on what measures or metrics would be useful for you to have (however complex and difficult they may be to track). Thanks!