The topic of "my P3 controller displays the voltage going to my brakes but not the current" has come up numerous times. I just came across this controller:
http://www.maxbrake.com/brake-controller.php
...which supposedly displays the current. It also applies current in proportion to the pressure in your hydraulic brake system. You screw in a pressure sensor to the master cylinder, which sends the pressure measurement electronically to the controller.
I've read some one-off comparisons from a few folks switching to it from the P3, and they said the braking was much improved. Smoother, at least.
Looks like it's $350.
Dave