I like using objectGUID for Sametime servers that use AD as an LDAP source as it avoids running the name change task which quite frankly no one ever did.
The one thing that bugged me was checking user’s buddy lists from within vpuserinfo.nsf which is harder now the users name is replaced with their objectGUID.
You can get the users objectGUIID by running ldapsearch to get their ldif. The value returned is base64 encoded as seen below.
This value does not match the documents in vpuserinfo.nsf.
If you get your hands on a Linux machine you can put the string through a decoder. There are web based alternatives available.
# echo rsfXUe2YI0uTmVfDZ0gMSQ== | base64 -d | xxd
0000000: aec7 d751 ed98 234b 9399 57c3 6748 0c49 …Q..#K..W.gH.I
If you add slashes after each two characters you can quickly see which document relates to the user.