OK, here is the new test NBH with the androidupdate.tgz. To make sure there is no funny business, please do the following:
Make sure recoveryinstall.tgz is removed from /sdcard/andboot
Put androidinstall.tgz and androidupdate.tgz in /sdcard/andboot
Flash the NBH
Do NOT touch the phone and watch to make sure it boots straight into recovery
Once in recovery, install like you normally would
This method is absolutely sexy! If recovery is ever corrupted for some reason, you can restore the original recovery by simply deleting init.recovery from the root
http://dl.dropbox.com/u/11790134/recoverytest.zip
Edit: Data does not work on first boot, but appears to work fine after a reboot!