A friend of mine has been shooting news on an EX-1, as the TV network I used to work for is pondering that same question.
Most of his concerns are related to weather, either indirectly or directly:
1- fragile compared to the big cam, and connectors not always in the best location (since there isn’t much real estate to begin with);
2- lens fogging, and you can’t remove it to air it out;
3- tiny controls which are hard to maneuver when shooting on the fly, especially with gloves.
I’d never risk subjecting an EX camera (or any other “prosumer” cam) to the abuse I saw our “big” cameras take at the hands of journalism school graduates (ahem) on a daily basis.
Cf