The latest Casio Privia's are surprisingly light (like 15lbs), sound and feel good. I erroneously recommended the Yamaha P45 to my inlaws last Christmas. At the same time my friend got a similarly priced Casio Privia PX-160, that I tried out (ironically when I went to visit my inlaws), and I immediately felt really bad, the Privia was in another class above the Yamaha... I've never had it in me to break it to them, though, they love it all the same. Kurzweils are a bit heavier, as even the lightest Fatar keybeds (like the TP/100LR on my Arturia KeyLab and on the lighter Kurzweils) are heavier than that. As for feel, I would say the Privia PX-160 and Fatar TP/100LR are comparable. Can't comment on sound or speakers, since I haven't played a Kurz for a weil.