See comments at http://musicbrainz.org/edit/30940729, where I inadvertently destroyed some disambiguation comments (on recordings) by merging one release into another. I was assuming that the comments would be merged as well, though now that I actually think about it, I can see that that could be problematic. But would it be possible to give editors a warning – "This merge will delete disambiguation comments on all recordings being merged," or something like that?