Coming back after having more multiplayer games with Tiger doctrines.
Changed my mind a bit. Tiger could prove usefull though but it's quite situational.
Well first, you gotta have intel. Best doctrine with Tiger these days was spearhead for me because of the recon plane. You should not throw the Tiger forward without knowing what's there. Playing Tiger with no proper intel available can make you lose the game (flares from OKW, recon plane from ostheer).
Secondly, your USF opponent must have no idea you are going for Tigers (and builds to many shermanns instead building some jacksons too. If he is caught on the wrong foot, he has little chance).
Your soviet oponent must chose a doctrine without IS2. If he choses an IS2 doctrine is game over for you. ISU 152 is acceptable too if you have proper intel.
Third, you need to be realy "shy" with your tiger at first and don't try playing Witmann
while it's still vanilla. Starting with vet 2 you can begin to be cocky and show what your tiger can do.
In the end, you will have to be lucky, too. In a 2v2 AT I vetted a Tiger untill 3 stars and at the end of match (when it died) it had 106 kills.
So you can use the Tiger with some good results but not in every match, it greatly depends on what your opponent does and what doctrine he chooses. As a comparison, on the soviet side, you can chose IS2 without trembling, it will do its job very well no matter what your opponent does. That's the difference.