We have used the meta title re-write for some time with the JOOMSEF and have found it unreliable because the configuration settings are not followed by the extension.
We have description and keyword re-write off and yet it keeps re-writing the descriptions and publishing them. We have our own descriptions and now we have had to turn of the title re-write which solved the problem with the description but now the titles are not being appended with the data the client wants.
This has been a compliant of mine now for several updates and support saying it can't be.
Well it is and it's a bug. My client is now asking for me to remove the Artio extension and go back to the old Joomla! re-write that at least 'worked'
That's not much of a vote of confidence. Between the menu ID tracking not working right and the meta data description issue I'm at a loss to defend the product. It seems to get worse each time we upgrade. I kick myself everytime I do and it goes wrong. As I see many users have experienced. Don't feel bad folks, it happens to all of us using this extension. Far from perfect at the core.
I would suggest sticking with the re-write side and not dabble in site maps and such. That's not what we bought the extension for. Lets get the core working right, that is predictably.