They need to have anti-roll over systems on those up-armored Humvees. Those things will roll over if you even sneeze at them. One of the bad side affects of adding the armor was to shift the CG much higher.
You're right. Here are a few examples of rollovers in Iraq.
http://www.freerepublic.com/focus/search?m=all;o=time;s=rollover
They should've added a LOT of armor to the floor pan, then.