Merkava-4 is the most modern of the series, featuring an American 1500 hp engine, a NATO-compatible 120mm gun (the earlier version all have a 105mm), additional armour on turret roof and reportedly modern comms and sensors (network-capable). With a weight of 65 tons, it really is no "light" solution. It has slower top speed and acceleration than the abrams or Leopard2A5 though.
And the following I found at Wikipedia (German). In the Lebanon war 2006, 50 Merkavas were hit and disabled by ATGMs and even IEDs, with many losses and wounded amongst the crews (over 130). Almost half of the tanks were disabled by hits that were able to penetrate the armour. Reasons for this relatively "sub-optimal" performance, according to the results of internal examinations of the Israeli defense minsitry were latest ATGMs delivered to Hezbollah, bad training standard and lacking experience of the crews, lacking mobility in tank tactics, and the units being fielded without smoke grenades. Also see here:
http://www.ynetnews.com/articles/0,7...297431,00.html )
I also belong to those few sceptics suspecting that their armour technology is not en par with the most modern Western "recipes".
The article refers to military officials concluding that Hezbollah had thousands of modern ATGMs and excellent penetration capabilities, and that it also had the knowledge and training to know about the characteristics of the Merkavas, and where and when to hit them to acchieve maximum probability for a score.
Under such circumstances, every tank is vulnerable, and faces extremely tough fighting conditions. I wonder how the famous American "Thunder Run" at Baghdad would have gone if their enemy would have been better prepared, organized and armed woith modern ATGMs (as Hezbollah obviously has been). I think they would have had far higher losses then. It was said that the Thunde rrun has chnaged the way tacticians think about the idea of tanks versus infantry in cities (before it was considered to be a bad idea). I still believe it to be a bad idea, at least against a reasonably prepared enemy with reasonably adequate weaponry. Thunder Run should better not be understood as an example to be repeated, imho. but maybe that is just me.
I just finished designing a Steel Beasts scenario where these risks for tanks fighting against ATGM-sequipped infantry became (involuntarily) obvious for me once again. It is only a sim, yes, but nevertheless one with high educational value on the matter.