I have issues with this rule point, about 3 things :
First(ly?) : as we discussed in the ''defense scaling'' topic, and as explained in the first update note, defense is now simbolized by resilience – wich is fine to me – BUT since you have the ability to spend 2 opportunities to inflict a critical hit to anyone, and that value not being modified by anything, your ''defense'' is not really well represented by your resilience.
Secondly : it create situations where you can take a critical wound without a single fatigue point, due to the armor; and that does'nt make any sense.
Thirdly : I don't think we need this opportunity spending option anyway : stances and katas gives way enough possibilities.
So I think we could try to abandon this option. I invite the GM to try not giving this option in one or two games and then report here the effects on play.