The decision for us is that with SOAR, it wasn't just a calendar (we had subscribed to the SOAR calendar through Google Calendar, so people could see the events on their mobile devices, etc.), it's that with SOAR, the calendar was also for sign-ups, and you could track who was signed up, and whether they had paid, and if they were bringing guests, how many guests were they bringing, etc.
The SOAR calendar also allowed us to allow others to sign-up for events, something Scoutbook doesn't allow for on their calendars.
And, it was all easy-peasy to use. Like someone else said, you didn'