The latest XB (with the default settings) has became much more sensitive wrt validation errors during XML parsing. This is mainly about the order of the elements in sequences. There are a number of JBoss configuration XML files (at the times of testing it's aop.xml, vfs.xml, etc) that can't be validated. As a temporary workaround, I am setting xb.builder.useUnorderedSequence=true, which will ignore the order in which the elements appear in the XML.
This should remain a temporary workaround and the wrong files and/or their bindings have to be fixed.