We're the back-end provider of the beta companies that are testing customer chat. As such, we're comparing the difference between Shopify merchants that you use it vs those that don't.
Will keep sharing insights here over time on the difference between a typically live chat and Messenger Customer Chat.
I really enjoy using Messanger, but I think having to be an FB user is a limitation in terms of business use. I wouldn't want my customers and potential customers, to be unable to reach me if they don't have FB.