touchmeinthemorning --
Remember Effie doesn't need to be fat (and several Effies haven't been -- Julia McGirt was downright skinny when she took over the role). The only reference to Effie's weight in the entire show is during "It's All Over" when Curtis comments that she's "been getting fatter all the time" -- well, that's because, unbeknownst to him, she's pregnant with his baby. Effie's replaced as lead singer midway through Act I primarily because her voice isn't smooth and pop-sounding enough for the Dreams to crossover, not because of her weight.
As for Heather Headley, I don't think she has the upper range for the part (she was flat and/or cracking on Lorrell's high notes in the concert -- Effie and Lorrell require the same upper range and go note for note with each other at times, especially during "Heavy").
I wonder if Jennifer Hudson can act -- early reviews from the road have pointed out Frenchie Davis' acting deficiencies and I wonder if Hudson would have the same problem. I imagine they both can sing the role though.
"What a story........ everything but the bloodhounds snappin' at her rear end." -- Birdie
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"The Devil Be Hittin' Me" -- Whitney