[otrs] Upgrading from 1.1.1 to 1.2.4 or 1.3

We've decided to attempt an upgrade of OTRS from our present 1.1.1 version to either 1.2.4 or the upcoming 1.3 We've been up 472 days and served some 1750 tickets. It took us that long to find a bug that actually required an upgrade. We are concerned about: 1-Retaining existing data 2-Rollbacks if problems occur 3-Upgrade methods I've tapped into the CVS but am not sure if I can easily move from 1.1.1 to either version. Is it a clean upgrade process or do I need to go through a few versions and 'stair step' things? Charles