Why Progressive springs are a bad idea

A test of Progressive springs showed they were really light for the first inch (like .45), about on par after the 2nd inch (1.05), and by the 3rd inch of travel they were so far beyond reasonable (1.7) that you'd never get any more travel. You limit the amount of work the forks can do (it's like installing a speed limiter at 60mph), which doesn't make sense. You want to use 99.99% of the fork travel when you ride your hardest (be that emergency stops or corners)... with Progressives you'll be lucky to use a Total of 2.5" (about half the total travel).

This all means that in more extreme situations, when you NEED your tires on the ground, the springs are going to fight you. Run over a 2x4 (that the suspension should soak up reasonaly well) and you'll have the front wheel in the air. Hit a pot-hole mid corner and not only will it be fairly jarring, but the fast rebound will reduce the weight on the front tire and increase the possibility of lost traction.

Progressive springs also have a bit of a problem with quality control. One of our suspension techs on the board reports seeing a couple springs that were drastically different from one another when pulled out of the same forks for service.

In the end, there's a known 'good, better, best' and Progressives fall squarely in the 'better' range. Riders only know the best they've ridden, so lots of people will report being happy with the improvement. If they felt the difference between the Progressive setup and the 'best' setup, they would agree that Progressives aren't worth the cost (which is about the same as normal straight rate springs).