1) sometimes, the freebusy simply is not displayed. One can see that when inviting sogo2 from the sogo1 account on sogo-demo.inverse.ca
2) when the organizer has no value, the CN is not displayed either
3) in the invitation window, when the COMMENT is not empty, it takes too much estate, which crops the list of attendees
4) on sogo-demo, Mail module, an error occurs when loading the module (warning sign at the bottom left corner).

All of this was tested on IE 8