I don't want to go too ot, but there have been many who added sensors to an rc outrunner, in the e-biking world actually.
Here is a link to a good thread over on one of their forums- http://endless-sphere.com/forums/vie...hp?f=30&t=9061
There are many builds on the forum that use an rc outrunner with an e-bike controller and in order to do that they need to add hall-sensors to the motor so that it would work with the controller. And I'm pretty sure that the sensored system used on an e-bike controller is the same with sensored model escs.