Well.
Considering I talk to people who are getting shot at in Israel almost on a daily basis.
I will tell you this.
The IDF guys absolutely love the M4/CAR15 over the Galil.
Keep in mind the IDF have units that fight in Cold Mountain climate, hot sandy desert and most of it all urban. They dont have the problems our soldiers have and I think that says a whole lot about the user of the weapon and how well they use PM.
Honestly the M16 series can work well in any environment included desert. AS LONG AS ITS CLEANED on a regular basis.
Sure the AK type rifles wouldn't have to be cleaned as much. But I rather have a weapon that lighter and I can hot what I am aiming at when its time to kill or be killed and have to clean my gun a little more.
BTW: The Tavor from what I hear is a great weapon.