I do not go to CF specific gym but my MMA coach makes us do it for one hour prior to training. I am super miserable while doing it ( tire flipping makes me wanna hang myself ) but the results are phenomenal. Cardio improved vastly and quickly. I can't speak for weight loss cause i am doing it for fighting only but i am sure its effective for that too.
A friend of mine goes to CF specific gym 3 to 4 times a week. She is tore up, leanest female i have ever seen.