No personal experience with their kits, but the feedback from level 1 owners that have installed them are that they love them. They do seem to provide the best all around suspension set up for a multi-use car. Are they the best, well, that depends on what you want to use them for. They are a bit light for serious autocross, they are a big heavy for serious drag use, but for handling, manners, comfort and ease of installation, it probably is the best stock based set up out there.
Since they developed their spring and shock rates on a four post rig, they were able to specifically match the necessary shock valving to their specific wheel rates. This is a luxury very few of us will ever have which is why for the average enthusiast, adjustable shocks are a much better way to go. Will their shocks work for rates outside of their specified amounts, sure, but they won't be optimal for the application.
It appears that their shocks are made by Afco. If you have the motivation, you can always contact Afco, discuss your spring selection with them, and get a fixed valve shock that is pretty darn close to optimal. They also offer adjustable shocks if you have the coin to drop on them ($400+ each).
