I just performed a test on our testbed to upgrade our client www.beerpong.tv.  I had no issues at all going from a 1.1 rainbow site to a 2.0 site.  Rainbow simply went to setup first and asked for an upgrade [ I think because I went from a SQL Sever 2000 db into a SQL Server 2005 restore] and completed with 0 errors.

Directions to upgrade your site to Rainbow 2.0.

1) Take latest 2.0 package and extract to your IIS directory.

2)Copy over your Design Folder.
  •     You must copy your 1.1 Design folder and replace the standard Design folder as this holds all your new Designs[UI]

3)Copy over your Portals Directory.
  •     You must copy over your 1.1 Portals Directory as this provides rainbow of your portal structure.

4)Load your DB backup and restore your web.config settings
  •     I took the fresh 2.0 web.config and just pasted my connection string.  However if   you have specific settings to your application you should copy all these values.
  •     Create a new DB and restore the DB with your DB backup with the latest changes.

5)Done

Note:  If you have specific areas where you changed such as DesktopModules you of course must copy this over.  Our client's site used standard 1.6 rainbow so this step was not needed.

Regards,

 Ramseur