An update for my X7 custom firmware is now available for download.
Most important, the calendar sync bug is now fixed. There are some other new modifications in this update as well, take a look at the (internal) change log for details.
I tested the calendar synchronisation on v3.2.0 via the latest Nokia Suite/MS Office 2007 on a Windows 7 x64 System.
Let me know, how this version is working out for you ;)