In terms of character design and animation style, yes. Setting, not so much, but I don't really think any of them take risks that way.

Absolutely yes, yes, yes. Sleeping Beauty is one of the most exquisitely animated movies ever made, and yet it was both financially and aesthetically risky.

It was the first ever full length animated film. Everything about the movie was a huge risk for Disney. It was even called "Disney's Folly" for a long time until it was released and ended up being successful.

It takes place during the 1900's (the most modern of all the Disney Princess movies in terms of setting), has a black princess, there are cars, newspapers, there's voodoo magic, the two main characters are frogs for most of the movie, and a lot of it takes place in a swamp (a very unappealing place visually). The setting is really different from Disney because mostly it's far off beautiful lands, which this is FAR from. The character designs aren't really risky, the only time that a Disney Princess movie had risky designs was in Brave. I'd say the most risky animation would be Sleeping Beauty because of it's very detailed and fake looking backgrounds. But I'm still going with The Princess and The Frog for it's setting alone because setting it around the 1900's is pretty risky for a Disney Princess movie in my opinion.

The medieval tapestry look of this film took a lot of creative risk especially considering the high cost of this film. Then I'd go with Mulan

easily! it took lots of risks and so much love and effort was put into it- and it shows in every small but gorgeous detail in the scenery, songs, etc. there is no other Disney movie (or any movie) quite like it and probably never will be. It has female heroes who aren't the usual pretty young lady, a progressive prince, a princess who is a little deeper than just a fairy tale maiden, and while the medieval art is obvious, you can see little late 50s details (like Rose's gray dress) that give it a little something extra.

but of course, Mulan's movie's gotta win.

What everyone else said. An artistic and financial risk.

I think Pocahontas too- I remember reading somewhere that the movie took 5 years to complete due to the complexity of the animation style. In terms of setting PatF probably took the biggest risk in comparison to the others.

Mulan and Sleeping Beauty would be tied for second