Well, I was a sceptic, but I took the plunge and fitted some Eibach Pro springs to my Mk2 172 and have never looked back! They are superb!
Ride is firm, but actually better than the std Renault setup, in my opinion. Handling is very good as std, but the Eibachs take it that little bit further, reducing roll and certainly ironing out the instability issues with the back end, especially over 100mph. On the track I found the Eibachs great too.
My only minor niggle is that they only drop the car 15mm up front and 5mm on the rear, but its a purely aesthetic niggle - the improvements in the handling far outweigh it!