Hello,
ARTIO JoomSEF version 1.2.3 should be compatible with Joomla! 1.0.11. We were cooperating on this with Joomla! security boys, so it should work together just fine. However, there is still a lot to clean up (in 404SEFx there was quite a mess in code), so please be patient if there are some minor bugs or so. However, let us know about them. ;-)