According with the data I have available, the M1A1 and M1A2 tanks indeed have Chobham armor.
The characteristics of that armor, and the way it is applied on the tank are secret. This applies for the M1A1/A2, the British Challenger 2 and the German Leopard 2A1/2A2
All vehicles have their negative points (sometimes all points are negative, like in the Sherman in WW2 or the pre-WW2 Russian tanks).
We don't know how many M1A1 or A2 have been destroyed, hit or damaged, because that is supposed to be classified information. Therefore we only have seen two M1 tanks destroyed, because the Iraqis took the area where they were destroyed, allowing the TV
stations to broadcast the images.
At least one of the M1, was hit on the side, which is consistent with the use of more powerful anti-tank ammo, such as the Kornet.
We should remember the Palestinians destroyed some weeks ago a Merkava-II tank just by flaming the engine with a Molotov Cocktail.
I have nevertheless noted, at least twice, glimpse images of very damaged M1's and destroyed UMVEE's, on Sky News.
The lack of information is actually quite comprehensive in a situation of war.
I think the embedded reporters are a tactical problem, instead of a strategic advantage.
Although hit, the M1, is of course, one of the best tanks in the world. As all tanks, it needs infantry support. Without it the tank becomes vulnerable, especially in cities, where it's use is not advisable anyway.