I'll throw my 2 cents in for someone that competes in street class.
Koni yellows work great on the stock springs. For a $500 suspension upgrade, I'm more than happy. The seem to work the best between 1/2 turn to a full turn from full soft (180-360 degrees). Much more feels over-dampened to me.
In autox, the car responds much better mid-corner and in transitions. Initial turn-in response feels the same, but there's noticeably less push mid-corner than with the stock shocks. Ride quality is improved even though the minor floatyness didn't bother me before.