Transitioning from r72 to r73 presented me with a challenge that I suspect is related to the shadow modifications in r73. Even after trying the latest version in master, the issues persist.
To demonstrate the problem, I prepared two fiddles. Here is the one using r72: http://jsfiddle.net/01xm6taz/3/ and this fiddle uses r73: http://jsfiddle.net/mtcq070x/2/
The main issue lies in losing control over the shadowCamera's frustum and struggling to find the correct way to toggle shadows in r73. Properly controlling the frustum is crucial for achieving quality shadows with a low-resolution shadow map, and being able to toggle shadows is equally important. Regaining control over the frustum will allow for different toggling methods (such as setting far and near to 0 or something).
If you compare the r72 fiddle, you'll notice that frustum control works in r72 but not in r73.
In particular, the following lines no longer function in r73:
light.shadowCamera.near = self.shadownear;
light.shadowCamera.far = self.shadowfar;
light.shadowCamera.left = -self.shadowleft;
light.shadowCamera.right = self.shadowright;
light.shadowCamera.bottom = -self.shadowtop;
light.shadowCamera.top = self.shadowbottom;
light.shadowCamera.shadowBias = self.shadowbias;
light.shadowDarkness = self.shadowdarkness;
light.shadowCamera.updateProjectionMatrix();
Although sticking to r72 is an option, it means missing out on some of the beneficial .toJSON updates introduced in r73.