Bought a Mixte for myself that was already out-fitted with a flat bar.
The lady who sold it to me also gave me the original drop-bars.
It's a japan built Raleigh branding with a 21" frame, which is the biggest I've seen in person.
From a comfort stand-point, the flat bars win over the drops.
I tried with the original drops, and found my weight too far forward.
It's currently set up with the flat bars on a pretty ugly adjustable quill stem and 28mm Pro-tite Pasela tires on the original 27-1/4" aluminum rims.
Cranks are a cheapie aluminum square taper set as well, and the bike left the factory as a 2 X 6.
I bought it for a grocery getter, and put a pletscher copy rear rack on it.
It's a very comfortable ride, and not that much slower than my Blue Rocket Motobecane Super Sprint.
Kalin makes a short reach 210mm tall stem that is reasonably priced, if she gets into over-reach issues with the drop bars.

-D.S.