It might be interesting to have a "no witnesses" rule -- if an attacking army gets completely wiped out, with no witnesses (e.g. via Astral Probes, stealthy units who remained hidden, battlefield in dominion and it's Arco) -- the attacker doesn't get a battle replay or info on the enemy force.
I'd suggest the same for defenders as well, except that it's possible that the civvies in the province might get word out to their former liege.