dont know..no real experience of koni..what i do know is awesome gti have vast experience.
i told them what i wanted which was adjustable suspension, that doesnt compromise comfort in real terms...three real choices....kw variant 1, eibach pro street, and koni...
we discussed and it ended up they stuck the eibach on (ironically made by KW), and its great. i have the KW variant 3 set up on my csl and its fooking awesome, so i knew the kit was going to be off good quality.
that ruled out koni, and seeing as kw make eibachs prostreet, they are effectively the same in ever way except name, but the eibachs were explained as slightly softer/compliant and also cheaper...
the comfort factor swang it for me, as i dont use if for track work at all, as i have the csl....
proofs in the pudding i guess....unless someone can tell me different i can only recommend the eiback/kw set up as i have it and it works very very well in the real world...no complaints about it at all.