I wouldn't throw a challenge. I think it tends to bite you, and as noted above, unless you are absolutely certain that the intended target will get hit, then you don't do it. Incidents can happen between the time of the challenge and trip to council. Those who thought they were safe can misstep and suddenly be gone. Just ask Nicole.
Plus, we might just see a mini-merge or tribe shift here, so gotta be careful about sticking your neck out.