These posts are reassuring. The UNC paths work, the NTFS permissions are as stated by Glenn Barnas, we have set the AD profile path for each user, and it sounds like there is no need for us to upgrade our version of kiXtart.
I did misstate something above - on the CIF server, we are sharing the OU folder, rather than Users or Secure. So, if an OU is ABC01, and has Secure and Users folders below it, ABC01 is the share. Users have full access share permissions and read NTFS permissions to the ABC01 share, and read NTFS access to Secure and Users, then full NTFS to their own folders under Users (inherit is disinherited to remove the other users). Does that make sense? Sorry for the mistype. Does it change any of the advice above?
I have one remaining question. Is the fact that we are using Prov-kix32.exe related to the fact that we are using @HOMESHR in the script, or is this done commonly?
For example, here is the script for one OU on the CIF:

;**********************************************************
; Arizona - Tucson Operations - El Dorado
;**********************************************************
IF INGROUP("AZ_TUS_Users") OR INGROUP("AZ_TUS2_Users") OR INGROUP("AZ_TUS3_Users")
? "You are now in the Western\Arizona\Tucson Operations - El Dorado Office"

? "Setting Time"
SetTime "\\DC01"

? "Setting Home Directory"
use u: @HOMESHR

ENDIF

? "Mapping Drives . . ."
use t: "\\Pdprv00nascif01\TUS03\Secure\"

ENDIF

Thanks so much for all of your help!
RRoati