We've had some Char crosses that are very efficient and some that were not. For quite awhile though the majority of our herd had some Char blood in it. We do prefer the Red Angus for many reasons but we still have some Charolais crosses that are excellent cows and doing their jobs. Here are a few pics, none of the smokey ones as we've never had black angus but I thought I would post anyway:
A five year old Charolais(sire) x Simmental/Red Angus (dam). The one on the left is her half sister on the dams side but still had a purebred Charolais sire :
Their calves at 4 or 5 months old (I deleted the originals so I can't remember the date). The sire of these calves is a purebred red angus:
An interesting cross (5 years old), she is Charolais (sire) x Highland/Red Angus:
Here is a Charolais (sire) x Hereford/Red Angus, again a five year old. The sire of the calf is Red Angus and he is about 6 1/2 months old.
The last cow is a smaller cow and doesn't take a lot to feed. The first two aren't quite as efficient but they are also not huge hay burners unlike some we have had in the past. Personally I prefer this steer though - 4 months old and one of our Red Angus freezer steers. His dam is small and doesn't eat much, plus she is 14 years old. Unfortunately no picture of her.
One last thought, a lot of people (us included at the time) preferred using a Charolais bull on our Red Angus cross cows (or Herefords or whatever for the main reason that the cows were more efficient. However, you will have more pulls doing it that way.