The FNS has been discontinued and replaced by the FNX. CDNN still has FNS models available. I just bought an FNX9 and haven't put any rounds through it yet, but it feels like a solid gun and one that I will really like. I've never owned or shot the Walther, but the mag release does seem hard to use in those I have held at my LGS. Not much help, but it's all I got.
I haven't seen the FNX yet but my cousin shot one and says he dosent like the ways it jammed a few times but I think it could be just it hasn't been broke in yet..only had about 20 rounds put through it