What you can also do (using the example of roto'ing a hand) is to create the roto much as you would a 3D character rig. The palm, the digits, each digit is made up of individual roto shapes for each joint/bone. Place the control axis at the center of the palm where it would pivot from the wrist. The individual roto shapes would then overlap for "joints" and their individual control vertices are placed in the joint area. Parent the finger joints (children) to each other in sequence and then to the knuckle joint, parent the knuckle joints (children) to the palm joint.
You have to create all of your shapes and parent them before you set key frames. Once animated, attached shapes will not follow. (Huge drag!). Once you animate the palm (all the fingers are following of course) you can then copy and paste the roto shape node. You can individually animate the fingers in the second node and hide them in the first node. Max the shapes together and you have a fully animated roto'd hand. This also allows for any motion blur that you made need to apply to individual fingers.
The same principal applies to rigid frame roto...cars, buildings, etc, etc. Attach tracking information to the base control vertice and everything follows along.
Much the same as previously mentioned, but potential for far fewer nodes.
K