I did not see Elka shocks mentioned in this thread. Elka offers an incredible amount of tune-ability in their Stage 5 package where a rider can easily make the necessary valving changes right from the clickers. Stack modifications are not typically required due to the broad range of external adjustment. You can dial them in for different conditions and then easily revert back to each specific setup based on the riding you are doing that day.
I'll mention also that changing the low speed compression for example doesn't change your high speed or rebound. Each setting is very much independent of the others.... Elka's clicker package is extremely refined. In terms of quantifying the upgrade, I would equate adding Elka shocks to adding 70hp. The change is that dramatic.
- Sean