In my opinion, the TIS modifier is likely spot-on. The most recent large East vs West tank battles were in the Gulf War/Desert Storm in 1991. The battle at 73 Easting pitting the US 2nd Armored Cavalry Rgt against a brigade of the Iraqi Republican Guard was fought at night, US M1/M3 type AFV's vs Russian T72/BMP AFVs. Even the movement to contact in the afternoon was in crappy weather. Fog, mist and oil-well fires choking out any chance of sunlight.
E Troop alone (10 M-1's and 13 M-3's, all with TIS) destroyed at least 20 T-72's plus other vehicles at no loss to themselves. 2nd ACR, a formation without significant infantry, effectively destroyed two entire heavy Iraqi RG brigades. These Iraqis actually fought valiantly and agressively until they were killed or rendered hors de combat. They just couldn't overcome thier inability to accurately shoot at Americans they couldn't see in the night, Americans who could see and shoot accurately at them first.
http://en.wikipedia.org/wiki/Battle_of_73_Easting
I believe the historical record supports the TIS modifier as realistic. It may not be "fair". but war is what it is.
Taffy