Hi Seanfod and chibaguy:
Keep in mind that the safest upgrade path is to replace your current installation of tiki 5.x with the new tiki 6, and not just overwrite the new file set over the old one.
This is (or can be) critical in cases where some template files are removed from themes, for instance, because your installation would be still using template files of themes from tiki 5.1 (or whatever older version you come from with upgrades through overwrites) in your new tiki 6 installation, and this may cause issues.
This has been one cause of many issues in the past in former upgrades from tiki x to tiki x+1 (or tiki x+2, +3, ...)
And in the mean time, you can test the upgrade process through the TikiLiveCD, for instance! (which can be used in conjunction with a virtual machine software like "Virtual Box", etc.)
Hope this helps.
P.S. And Seanfod, please helps us update the documentation about Upgrades if you find any unaccuracies in there while you review the steps to do the upgrade. Thanks!