Variety talks 3D with Paul WS Anderson in The Three Musketeers

Variety has an article discussing some of the benefits of filming in true 3D, focussing on The Three Musketeers.

The sword fights benefitted especially from the 3D. While the added dimension doesn't support traditional stunt fights where blows don't actually connect, sword fighting can look great because it depends on the real impact of the blades. Anderson wanted the sword fights as real as possible, because 3D scenes aren't cut as fast as 2D, which means one can't rely on stunt doubles due to the sustained takes. Sword master Nick Powell was charged with coming up with some impressive fencing scenes that the actors could actually perform, without wire work, tricks or CGI -- the upshot being that they all wound up becoming proficient sword fighters.

Anderson points to a little extra dividend: "When the blades hit there are these fantastic sparks, and I know people are going to assume they were added in post-production, but they're all real because those are titanium blades. And when they clash, sparks fly."