Here are my OZ quick installation and bringup notes for the somewhat lazy.
When I first picked up a 5500 a few weeks ago I went through the following steps:
Installed the latest OZ-gpe since I wanted X, not qpe.
Encountered instability - perhaps due to operator error.
Installed the latest OZ-OPIE.
Found the Cancel button bug.
Couldn't get the WCF12 up immediately.
Installed Hentges' latest OPIE, skipping cardfs (for the too-big card-found-dialog bug).
Copied cardfs.bin from Win2k onto FAT SD then to 5500 memory.
Formatted SD as ext2 and moved cardfs.bin back to SD.
Installed cardfs from the cmd line.
Manually moved /home, /opt and /etc to SD (no need to remove the card) then sym-linked /media/card/home to /home, etc.
Brought up WCF12 with no issues.
Browsed the unstable OZ feeds from a desktop machine and scripted the:
ipkg install -d sd <stuff>
ipkg-link add <stuff>
for the packages I wanted.
Tried the OPIE PIM and mail and was vaguely unhappy with it so I installed KDEPIM 2.2 (to have the same version as the memory-stick).
Copied the mem-stick kapi/kopi to a usb drive and synced it to the 5500 with no issues (from Win2k box).
SFTPd from FileZilla with no issues except adding password to root.
ssh'd from cygwin with no issues.
I spent no more than ten minutes on each of the first two ROMs above before trying something else. What took the longest in Hentges' was deciding to always have the SD mounted.
Now I have what I wanted from the 5500: a relatively stable PIM/mail system that I can do some c, octave and perl work on. Since mail is IMAP and kapi and kopi stay synced to my desktop, all I have to do is zip my source code and pwmpi.data (ok, and wellenreiter dumps) and send it to gmail every day. That way I can try 3.5.4 gpe after pre with only a quick update to my-ipkg-install.sh.