[O] Reading calendars in org mode: what is the best solution?

[Alan Schmitt]

Hello,

I would like to have a read-only version of my calendars in my org
agenda. These calendars (10 of them) currently live in Zimbra and
iCould, and I am accessing them both using the native Calendar
application on OS X and on my (Android) phone.

I've looked at what the options are, and I can find two of them:
- convert ics files into org files 
  (http://orgmode.org/worg/org-tutorials/org-google-sync.html)
- set up a synchronization using caldav
  (https://github.com/dengste/org-caldav)

Note that I don't want to edit the calendars in org mode, I simply want
to see them in my agenda view.

My questions are: do you have something similar set up? And if so, is
there a preferred approach, and gotchas I should be aware of?

Thanks a lot,

Alan