The other threads cover the installation and issues with respect to it and other general discussion, but I am most concerned with this one issue. The limitations on using the External SD card and the ability or inability of developers to work around it could determine if it is worthwhile to update or not with the official based firmware.
An example is currently being able to have large (almost 2 gb) GPS map files relocated from internal SD to external SD with build prop changes - will that even be possible with official KitKat?
I would like to see users post their results in this area alone here, Otherwise they will be spread all over the other threads. I have not flashed it yet due to installation issues, but when they are sorted out, this one problem are may still make it not worth the effort.
Update - it looks like there may be an easy fix:
If that does not work as-is on M919 - probably will be one soon that does.