My sense is that the VT fusing "as written" is all reward with no risk. VT fusing had nothing to do with the ability to aim the ordinance - and (in response to MattW) this is why US/UK/GER artillery has the 1:6 not 2:6 chance of FF (i.e. that codicil already accounts for on-target accuracy). In reality, if the fire was off-target, the damage due to the air-burst would not discriminate between friend and foe.
Of course, any introduction of "home rules" complicates matters and, perhaps, that in itself suggests not tinkering. But I can't help but believe that a +1 or +2 shift to the d6 roll for the Bombardment Fire column for a FF VT event would make the US player weigh their options a bit when units are adjacent and be more reflective of the fact that shells are a two-edged sword. :
cratches head::
