The ability to aggregate multipe calendars into one and to easily subscribe to these aggregated calendars would be a nice features. Someone could have multiple calendars, and people who want a view of these (and have viewing rights rights) just need to subscribe to one CalDAV feed which serves the aggregation of these calendars.

We use a few calendars each and subscribing/managing subscriptions to them is a bit of a hassle. We mostly need only viewing rights for these calendars, and subscribing to an aggregate view would be convenient.

Having an option in SOGo to automatically subscribe to another user's calendars (with availability depending on the permissions set) or to publish an URL with an aggregate of one's own selected calendars. would be a nice feature.