I was riding on Bec-Techs(with Eibach pro-kit springs) for almost a year before I changed them.
Originally, I just wanted the lowered look and wanted to be able to set the car to any height I wanted, I wasn't really interested in performance then, just lowered nicely and riding like stock. So the Bec-Techs were for me, at least at the time. They were ok, comfortable cruising but bouncy on uneven roads and were too soft when cornering. But if it was a lowered, comfy, cruising ride you were after, they were good.
I've since changed to KONI true coilovers, and the difference is night and day. The ride, pretty much like stock, not harsh, not bouncy, just very nice and with height and ride adjustment it really is a world of difference. And the quality of the KONI suspension, top notch!
That's just my experiences.....