If WDAA will recognize that training & showing in low levels while riding two handed in a curb is the antithesis of low level dressage and make their rules align with that: I'll go with WDAA. The rules in NAWD make more 'dressage' sense, customer service and proofreading skills aside.
Just sliding in for a righteous rant:
Good lord, riding two-handed in a curb bit is anathema to *everyone* worth paying attention to. Good trainers in Western World don't do this.