I'm really hung up on that early 20's thing too. I mean, there are plently of women in their late 20s, 30's and perhaps into the 40's who would be a great, youthful Poppins. I'm in my early 20's and unless they found someone both mature a la Benanti, who reads much older anyway, I think it would be pretty awkward.
"This ocean runs more dark and deep than you may think you know...I'll be the fear of the fire at sea."
-Marie Christine