After 4 days, I can say that my system is running normally. It took it about a day to settle down though. Anyway, while reading the Nav training manual that is a sticky on bimmerboard.com I uncovered something interesting that I feel should be shared with those considering v27 upgrades:

quote from page 73:

"After the navigation computer has been successfully programmed and coded, the vehicle should be left in an area with a clear view of the sky with the key in KL R for at least 15 minutes to complete the calibration process."

Apparently, the new software will need to find satellites and set up almanac data. Perhaps this is what is at the root of the v27 upgrade related "lost position" concerns. It would appear that the nav system needs to calibrate the gyro as well during this period. At any rate, it certainly can't hurt to perform this final step whenever a nav upgrade is performed.

wow, the nav screen is supposed to adjust with the sunlight. I don't think that feature is working on mine.

sigh

MKIV brightness test:

In a dark garage, set your screen brightness to lower than quarter. Now, use your glovebox flashlight and shine it on the sensor that's directly under the screen. The screen brightness should increase. If not, you need a new screen assembly.

You don't want to know how much BMW charges for that part either....