Ok. I've done some research on this. Here is the FAQ entry in question:
34) You stated before that the Standard of Concealment helps against Hail of Arrows. In what way exactly? Since the opposing leader just needs LOS to the unit and uses his LD, the penalty to RC does not come into effect at some point. Is the penalty to RC translated as a penalty to LD or DAM?
*** It is translated to the LD score of the Leader making the roll.
Now, admittedly, this opens up a rather large and ambigous can of worms.
If we assume that the above entry is correct and the intent, which we have no reason to believe otherwise, that leads to a very interesting set of situations.
Based upon the above interpreation, it would seem that the LD penalties for Chameleon would transfer to the LD roll for HOA.
Do I agree with that? I am admittiedly torn. Cases for and against have an equal validity.
The similarity between the Standard of Concealment and Chameleon is that they both, in theory, affect the vision of the enemy units, blurring their view and making them less visible.
HOA does not require an RC roll, instead requiring a LD roll from the Leader to correctly judge the placement and direction of the HOA. If the target is not seen as clearly, that placement, even for a large volley of arrows like HOA, becomes more difficult, and potentially less effective.
This, I believe, was the intent behind the FAQ ruling as stated. Which is why I believe it should apply to Chameleon, as well. As the situation would appear to be identical, just that the Reapers have a built-in, and much more effective Standard of Concealment.
Is Chameleon effective? Without a doubt. However, as, if memory serves, the Reapers are the only models with Chameleon, I don't think it is that much of a problem.
Now whether this creates other situations with other models I do not know, and would require further research.
On the other hand, I tend to be, as most know, a strict literalist when it comes to the rules. Although the above copied FAQ posting does seem to set somewhat of a precedent.
Regardless of whether it should or shouldn't apply, there is always one element which throws just a pinch of randomness into the mix: deviation. HOA deviates if the LD roll is failed, which, depending on the blessing or damnation of the Dice Gods, work for or against either side, as deviations are notoriously fickle.
It could be argued both ways.
SP