Finally got IUpdateable.ResetResource() for Linq To Sql working correctly. This means that REPLACE operations are now working correctly. I have uploaded those changes to code gallery.
Going forward all changes to the code with be available exclusively on code gallery. Also, I am trying to track known open issues there with the issue tracking capability.
Finally, if anyone wants to be a contributor to this project or the SubSonic one, please let me know. Particularly for the latter, there is some considerable work to do.