Nautilus is managing the desktop.
So using unity-tweak-tool, if you set the cursor theme to dmz-white by hitting the "restore defaults" button
glen@Raring:~$ gsettings get org.gnome.desktop.background show-desktop-icons
and then select "use large cursors", is the size consistent? Isn't here.
The "use large cursors" appears to just change this dconf setting (default is 24)....
In 12.04 & 13.04 the only way for me to get a consistently large cursor is to use a cursor theme that only has one large size.
glen@Raring:~$ gsettings get org.gnome.desktop.interface cursor-size
HERE, where I removed the 24 and 32 pixel layers from the DMZ-Black theme so it has to use 48.