I've noticed the bombing site problems as well. Sometimes it comes up short and sometime it goes long. Side to side seem alright from my testing....
As for the Long Tom It's amazingly powerful. I pegged an awesome that appeared undamaged in the center torso at 500m and it died instantly. Not sure if maybe that's a bit too powerful. I'd like to see it do a bit less on a direct hit but have a bit more radius with it's splash. Would also be sweet if a dot would appear on the map showing the estimated hit location. Not sure if it's something that fixable, but the trajectory estimate does not seem to include colliding decorations like rocks, makes it hard to use the long tom on inferno where decor rocks seem common.
Now on the flip side, the Long Tom is quite expensive, the ammo is expensive (prohibiting random fire), it handles like a brick, it's large and easy to spot from the air while passive, and has pretty paper like armor.