A year and a half ago we abandoned using Cadence and Altium in favour of KiCAD. Extremely high cost of licensing was a reason, but not the only one. Our first steps with KiCAD were hard and tiresome, my engineers even tried to sabotage the work a couple of times. But now as we got used to KiCAD I'm pretty much happy with this decision. KiCAD's GUI needs rework, also its net naming convension is flowed (try to re-annotate the whole project an you most likely will lose your PCB design because of incompatible net names). Yet, if you understand what is going on under the hood you can work around the issues. Since we switched to KiCAD we have been able to successfully design (and test) a couple of complicated PCBs with DDR3 and 0.4mm pitch BGAs. In this regard, I would be happy to see more ppl starting open source EDA projects. A decent Gerber editing tool is a need!