No, but if you must move to a more rapid update schedule (as the Firefox developers clearly felt they did to stay competitive with Chrome, since users were screaming against rapid release from practically the moment the plan was announced and they went ahead with it anyway), moving the rapid updates into a new product is less disruptive than shoehorning them into your existing one.
Rapid updates doesn't need to be disruptive, look at Chrome. I don't think Firefox users will miss the Update Dialogue if they removed it, and did silent updates as Chrome. Fragmenting into two apps, and keeping an app with slower update cycle and a crappy update experience, seems bizarre.
