I asked my father, and he says that in Maricopa County, pacing is an acceptable method of measuring speed, and the citing officer can give opinion and testify to the court as to how fast the plaintiff was going, but it's ultimately up to the judge to decide.
I'm sure if you go in, and you don't look like a scuzzball, you'll at least get some sort of break. I didn't have my insurance card, and the LEO that pulled me over (for not having headlights on after "dusk" [7PM in the summertime]) didn't wanna let me go to my house 2 blocks away, oh well, letter of the law, not the spirit, so, he ticketed me. I went to the East Phoenix JP and got it sorted out, and reduced from $450 to $222. Cool.