[Riing Fan As Case Fan]

What is everyone's opinion regarding the riing fans? Can they be used as case fans? I think they look really nice and clean with the led ring compared to the led lighted fans that emit light on all four corners.

 

However, I read that these fans are geared more towards radiator cooler applications as opposed to airflow case fans. Is this accurate or will there be a minimal loss in airflow when using these riing fans?

 

Are these 3-pin or 4-pin fans and will they work with PWM?