I have been through this many times with other Spring projects (not to mention version 1.0 of this project). It is a matter of choosing to feel the pain now, or feel he pain later. In my experience, it's been easier to instruct people to configure it manually in Eclipse for the milestones (and they've usually been perfectly fine with doing so since it's pretty simple to do), rather than figuring out how to clear Eclipse's incorrectly cached version later (which has historically been harder to achieve).
Plus, the errors that show up in the XML editor, though annoying, in no way effect the ability to actually run the application, so it is not preventing anyone from trying the milestones.
From my perspective, it's much better to have to deal with these little annoyances in the milestone phase (where it is generally accepted that things such as the tooling not working perfectly out-of-the-box come with the territory of using dev releases) than to have them surprise people in the GA release.
Staff Engineer, Web Products Team