Interesting thought exercise. I have to say I never considered the infantry in game too fragile. If at all, I usually find myself wondering who in the world would keep fighting like some troops do in game. Assaulting AFVs, a common occurrence in game, seems pure insanity to me...Than again I generally consider infantry types to be a bit nuts
Frankly, I think alot depends on the time and place, not only the unit itself. I believe the same unit can break from 10% loss or keep fighting with 30% losses. IRL if you took 10% but you see that really the only possible outcome is death and defeat you will probably route, on the other hand if you take 30% casualties but the battle is still winnable you may very well fight on...Consider that the IDF 188th armored fought on until it was physically gone- 90% or so tank loss(started the 1973 war with ~70 tanks and finished with less than 10, removed from IDF OOB officially!).