[Agema]

My perception of magic bows on heroes is that by and large you're still just hitting one unit per turn, and when I say "hit", I mean IF the arrow hits a square with a unit on, and IF it isn't parried by a target's shield, all of which means your average magic bow is pretty ineffective in terms of stopping an army.

The exceptions would be bows with area effect or multiple arrows. I figure 5-10 indy commanders with a bow of war would be a good archery force instead of about 50 archers, but you've probably got better things to do with your gems. Banefire crossbow I think has AoE 1, and a few others.

Where you may well get most leverage is assassinations and tackling thugs, and even then you probably need a precision booster to make sure you hit. An assassin with the right bow should be dangerous to the average mage without a bodyguard, and several bows might be very effective at downing or disabling thugs if can deploy them.