MCI is sooo bad, I wouldn't even switch if they went back to the old 25,000 mile promotion.
Last year, I signed up for their "stand alone" calling card offer. I made one or two "one minute" calls just to qualify for the 1000 miles each month. Needless to say, I had to call them again and again. I think I still came out on the short end of the stick.
Now days, I use the Sprint calling card and pay .035 cents per minute without miles. Considering how many other ways there are to earn miles, fooling around with MCI just isn't worth it.