As already stated, your best bet is to ask the TO. If it were my tourney, my answer would be pick one and stay with it. Same answer GW gave for BT vows back in the day.
Hmmm........... Let's see, a vow that affects the entire army or a majority of the units by giving it a special ability vs a character that affects the entire army or a majority of it by giving it a special ability...... Hmmmmm, really, looks the same to me. Except that BT used to get it for free which is why it became a tourney question. No points cost, so why can't I change it between games, it's not changing my list.......... Yeah, right, tell me another one.i dont think that the vows of the BT are a good refrense as the vows are a upgrade this is more a special rule. and its a option you can swap the combat tactics you dont have too and thats what makes this so difficult too rule. i think different TO's will have different rullings
but personally i think its fare too swap tactics its pretty clever this way you can maximise the effect of your army do you need extra though men or more scoring units.
That would be true if I hadn't specified OLD rules back when they got it for free. Reading comprehension - fail................:laugh:The Black Templar comparison is flawed anyway as you must pay different costs for each vow, you might as well be swapping out wargear as changing vows.
And this is the only real answer. Ask the TO. If you're coming to one I'm running, don't bother with taking two expensive characters..But I would definitely clear it with any tournie guy first before just springing it on someone.