I've see that this thread existed over a year ago and there probably have been more recent ones.
I do think however, architects would really benefit from an export shadows only option for post production purposes.
I have witnessed colleagues resort to corona, v-ray etc for render purposes simply because Enscape does not offer it.
I, myself would extremely benefit from an export shadows only option as part of my work flow an i am all for Enscape rather than other rendering software's.
Please try include this option in upcoming updates if possible.
Thanks for reading.