Question about migration from exchange 2003

[syaginf]

Greetings.
We are currently using exchange 2003 but hopefully going to switch to zimbra.
We have groups of people who need to share calendar and the right way of doing it seem to be to use calendar in public folder.
Since we plan to switch to zimbra we are trying to figure out if we want to continue doing it this way or create fake user and just share his calendar (seems like terrible idea) but hoping it's easier to migrate specific user calendars.

Ok so the question is - Is it possible to migrate public folder calendars to zimbra or it is easier to migrate shared calendars belonging to specific user.

Thank you.