There was a very unique unit made by TheLopez that I'm not sure if it could find its way in. He made a sniper mod, however it was for 1.61 and he hasn't been actively developing since before Warlords edition, it appears.
Anyhow, I thought the idea and implementation for a sniper unit were very good and would have some use in these WWII games. Whether in this particular one I will leave up to you.
Reading the sniper mod thread, it appears Dale converted the mod to work in Warlords. Presumably, it has not been done for BTS as of yet -- so it would bring something of a challenge.
Another thing I didn't like about snipers, what's a sniper's max range? About 1-2km? Doesn't quite work with Civ's plot sizes.
At least arty can fire over 10-30km (rocket assisted) by the end of the war.
How will terrain capture work with peacetime allies? If two civs allied approach a city from different sides, will the person who captures the city gain his ally's squares so the city can grow, or will he be restricted permanently (because he would have to attack to get the squares).
He should gain the ally's squares, shouldn't he? Thoughts?