WHICH options are you using? 
I remember I did some experiments with strarc option -r to backup the registry, but was not happy with it.
I don't remember why (I think ERUNT was doing it much faster), so I will redo tests with this option,
as it might be useful for the Total Update including the User Registry.
At the moment I am using for driver Update as piece of AutoIt3 code:
RunWait(@ComSpec & " /c makebt\strarc.exe -cd:C:\WINDOWS\system32\drivers | makebt\strarc.exe -xl -s:c -o:n -d:" & $tmpdrive & "\WINDOWS\system32\drivers", @ScriptDir, @SW_HIDE)
RunWait(@ComSpec & " /c makebt\strarc.exe -e:.PNF -cd:C:\WINDOWS\inf | makebt\strarc.exe -xl -s:c -o:n -d:" & $tmpdrive & "\WINDOWS\inf", @ScriptDir, @SW_HIDE)
RunWait(@ComSpec & " /c makebt\strarc.exe -e:\ -i:.exe,.dll -cd:C:\WINDOWS | makebt\strarc.exe -xl -s:c -o:n -d:" & $tmpdrive & "\WINDOWS", @ScriptDir, @SW_HIDE)
RunWait(@ComSpec & " /c makebt\strarc.exe -cd:C:\WINDOWS\system32\CatRoot | makebt\strarc.exe -xl -s:c -o:n -d:" & $tmpdrive & "\WINDOWS\system32\CatRoot", @ScriptDir, @SW_HIDE)
RunWait(@ComSpec & " /c makebt\strarc.exe -cd:C:\WINDOWS\system32\CatRoot2 | makebt\strarc.exe -xl -s:c -o:n -d:" & $tmpdrive & "\WINDOWS\system32\CatRoot2", @ScriptDir, @SW_HIDE)
and for Total update:
RunWait(@ComSpec & " /c makebt\strarc.exe -cd:C:\ | makebt\strarc.exe -xl -s:c -o:n -d:" & $tmpdrive & "\", @ScriptDir, @SW_HIDE)
and for Registry Update using the previously by ERUNT saved registry in folder SYSREG
FileCopy(@WindowsDir & "\ERDNT\SYSREG\SAM", $tmpdrive & "\WINDOWS\system32\config\", 9)
FileCopy(@WindowsDir & "\ERDNT\SYSREG\SECURITY", $tmpdrive & "\WINDOWS\system32\config\", 9)
FileCopy(@WindowsDir & "\ERDNT\SYSREG\software", $tmpdrive & "\WINDOWS\system32\config\", 9)
FileCopy(@WindowsDir & "\ERDNT\SYSREG\system", $tmpdrive & "\WINDOWS\system32\config\", 9)