ok so I'v taken a look at your version, it looks great, alot more balanced than what I have.
I especially like your Modern Sniper he look really good with the cammo gear
my only main complaint, if you could call it that
is that the WWII sniper is doesnt have cammo, unless you were trying to achieve an urban combat look in which case I think you have suceeded.
The way I made the unit invisible was to edit the Civ4basicinfos file in the Basic Infos folder and create an invisible sniper exception ( for lack of a better term) just like you would for a submarine. here is where i edited
<InvisibleInfos>
<InvisibleInfo>
<Type>INVISIBLE_SUBMARINE</Type>
<Description>TXT_KEY_INVISIBLE_SUBMARINE</Description>
</InvisibleInfo>
<InvisibleInfo>
<Type>INVISIBLE_SNIPER</Type>
<Description>Snipers</Description>
</InvisibleInfo>
</InvisibleInfos>
<UnitCombatInfos>
this will allow you to create invisible snipers and allow them to be seen by other specialised units. Also I do agree with other that there should be a weakness against armored units. But other thaqn that great work look forward to seeing what you have next instore for us