Ok, let me put the question into an other form:
What is different in using the "xen-create-image" command and the commands used by your howto to build a domU ?
I admit I'm no linux or programming professional (not even close), but as far as I understand it, the "xen-create-image" command (from the xen-tools) is some kind of a perl script.
By looking deeper into the file I figured out that it does basically the same as your howto recommends.
Do you create domU's with this tool or do you hand-craft them ?
Have you ever compared domU's created in those two ways ?
I tried to compare the one built after the howto and the other, tool-based domU.
As far as I can tell, the both aren't that different (not to say they are equal).
The automatic created one is a bit bigger, uses some different fstab entries and uses sarge instead of stable in the sources list.
But I doubt that these minor differences can change the proper working of domU's.
Maybe there's something I've overlooked.