By proportional, if you mean the harder you press the brake, the more braking is applied through the controller to the trailer brakes, then yes. At least on the Fords they are. Mine shows the bars and increase as you apply more brake. Works very well. I do not know about the Dodge or Chevy integrated controller, though I believe I remember hearing somewhere that the Chevy was also.
Ed and Sharon
2010 Wildcat 28RKBS
2011 Ford F-250 XLT, 6.7L PSD
Ride-Rite Airbags and Airlift wireless remote compressor...nice!
I thought I was wrong once, but I was wrong!