I don't know how the balance could move, but if I refer to this:
The rules quoted above could be found there: http://www.dragonheelslair.com/en/rulesbrandubh.php
Main changes are that King is captured by only 2 attackers everywhere (even on throne) and the throne is not hostile. This explain why the balance is -1.15.
This is why I proposed something a bit less in favor of attackers. Even if I suspect the "noreturn" variant will be the more balanced.
It could also be possible we have to combine the 2 variants to balance the game.