Damn... That's a lot of money for something that probably equates to a variable resistor. Unless they jack into the wiring harness, which for me is a big no-no.

I'd vote for the PCM. It's the correct way to tune.

A true happy knob goes along with a special pcm tune that will take advantage of specific resistor values for advancing the timing. Really, it's only beneficial for the track in my opinion.