I got my Koni FSD's from Larkspeed many years ago and am still very happy with them. They seemed to go out of favour after several cases of severe rusting were reported and Koni did not appear to be too helpful in sorting it out. Quality of the latest shocks is said to have improved and I would buy the same again if they ever wear out.
I'd also check out the Monroe reflex dampers to see if they have similar 'frequency selective' damping characteristics.
Many good folk on here such as young Spike have had no problems with the FSD shocks, personally, my counsel would be to avoid after the failure we had.