Here's a good tutorial from the same supplier I linked on the controller. They sell both controllers, so I don't think they stacked the deck for either controller design. Their explanation and pros/cons are why I go with proportional vs. timed. With automatic leveling and 360 degree mounting in the modern proportional controllers now, the negatives are all but gone. Still, the reason there are still two designs is because folks have different views and preferences on some of the differences.