Using MDA as a DA in a continuous descent isn't quite the same as the DA for a precision approach. You're still not permitted to descend below the MDA, unlike a precision DA. This means the a/c must have either commenced the missed approach prior to reaching MDA or have reduced RoD enough to ensure inertia will not cause a bust below MDA when the missed approach is commenced.
Our company uses a Company minimum of MDA+50' as a buffer to minimise MDA busts.