I use ODE (aka OpenDE) since ten years, I have integrated it with a scene graph an a dozed of other opensource libraries, and that's my dev env. So no Unity for now for me...
You are (quite) right, angles would only suffice to replicate a hand pose between two different scale hands - yet the problem with the Borst-Indugula spring-damper attraction method is that an angular velocity has to be calculated, and that's not so easy to accomplish - so presently I only do it for the palm (for which such calculation is simpler, and which, due to the larger mass wrt. phalanxes, the help from an angular attractor is mandatory for a fast response), and use linear attractor for all #16 hand bodies.
On the other hand directly apply sensor data to a physics hand is out of discussion - as you could have experienced, dynamics bodies only want to be moved by applying forces, not by direct positioning (position is infact the final result of the integration), the latter only leads to instabilities.
A model like the spring-damper one also improves hand-object collision response, which is far the most challenging topic to research on, beecause pysics hand bodies tend to interpenetrate virtual objects much less thus letting the collision detection work much better due to thin penetrations.
Performances: I love when CPu cores all work, in my system dynamics simulation (including collision detection) is one thread, graphics another one, LM driver has room on a third one, collisions audio feedback and few other light tasks go on a fourth, so I think a 4-core i5 would fit perfectly such an application. In other words, non-GPU accelerated physics simulations should get a dedicate thread/core, yet this usually results in houndreds of sim cycles (I get 300 to 500 Hz simulation in a complex dynamics world populated by tens of complex trimeshes depending on how many collision points originate fron the collision detection, which is the heaviest phase of the simulation).
Thanks for the suggestion, glad to talk about physics-assisted interaction with an expert on the LM side.
Paolo