It did work for me with modified xml, your code and your STRANS code.
Now I remember, there was one more thing that I changed.
SOURCE XML gt_itab was changed to SOURCE XML lv_string
lv_string is type string and has entire xml.
I have always passed xml as a single variable of string type, not as internal table.
As for larger xml, specifying the namespace in just the root element is enough. The child elements would simply inherit the namespace.
If xml is improper, it needs to be modified before passing to STRANS.
If you paste your xml in XML Validator, the validation will fail.
Note: You can avoid the dumps by catching the exceptions using try..catch..endtry block.