The latest archive of MacTranslator (testet with 0.10 and 0.11) from http://sourceforge.net/projects/mactranslator will produce a checksum error on decompression, whereas BOMArchiverHelper.app will do just fine. If you do the decompression in PathFinder instead of Finder, The Unarchiver will not even display the dialog box containing the error. This freezes The Unarchiver and leaves no option to decompress any more archives.
I assume both of the described problems are bugs?