well I have used it and it seems great so far The only issue I have is if I label the AP s found and i export them . then on a fresh installation the label did not re import back maybe i am doing something wrong ?? cause i have squite some AP s near me !!! and i format the pC quite often !!
in 9.01 and below you would need to back up these files(this is the default location anyway)
C:\program files\Vistumbler\Settings\manufactures.ini
C:\program files\Vistumbler\Settings\mac_labels.ini
Since 9.1 Beta 1 I changed to using a database file for manufactures and labels(necessary to support all manufacturers). So you would want to back up this file from now on
C:\program files\Vistumbler\Settings\ManuLabInstDB.mdb
After you install vistumbler just replace to new ManuLabInstDB.mdb with your backed up file
Also to note, Vistumbler does not load labels in from a save file. When importing the labels are regenerated based on the labels in the ManuLabInstDB.mdb file.
Just to let you know I changed this again today. I realized from you post that if I use a single DB file for manufacturers and labels(ManuLabInstDB.mdb) then if i need to update/add manufacturers it would wipe out everyones labels.
So, The new new file (9.1 Beta 3 and above) you want to back up is
C:\Program Files\Vistumbler\Settings\Labels.mdb
Sorry to anyone who has added labels, this change is going to put them back to defaults. From now on though this file should remain untouched unless I have a good reason to change it(and if that comes i will try to figure out how to preserve everyones existing labels).
The only issue I have is if I label the AP s found and i export them . then on a fresh installation the label did not re import back 
maybe i am doing something wrong ?? cause i have squite some AP s near me !!! and i format the pC quite often !!
