I have the FSD's with Eibach Pro springs....
Not as solid / hard a ride as the FK Highsport coilovers I had on my MK4 Golf but it is much better than the standard crashy suspension setup. It has probably only dropped the car 10 - 15mm from the standard LCR ride height as the LCR is the lowest model of Leon already (Would look more of a drop on a LC I think).
I have since had Neuspeed front and rear ARB's fitted, this is what really makes a difference, I wish I'd have done them first really. The Koni FSD's 'are' good in my opinion but if I could choose my suspension again I would pay the extra and get Bilstein PSS9 coilovers. I would just like to drop my car a little lower (5 - 10mm more) and I would like to have a slightly stiffer setup / feel the road a little more... Thats just my personal opinion, don't get me wrong, the Koni FSD's are a great shock absorber, it's purely down to self preference.