Hello - I just wanted to let people know what my first impression is of the casio Privia PX-555R.
I decided to order it sight unseen, because of all the good reviews about the keyboard action and sounds of the Privia models, plus I was able to get one in Canada for only $673.65 cdn. with free shipping. It was a recondioned unit. I've only had it one day, but after playing on it for a couple of hours and playing with all the buttons and different settings, I have to say VERY NICE! I also own a Yamaha U1 upright piano, so I can easily compare the keyboard action on both, and like the others have said, the keyboard action on this thing is very nice, a little stiffer than the acoustic but I like it better, because I can "dig in" better, very smooth, not clunky at all, and the keys do not bottom out hard if you know what I mean.
The sound through the speakers is OK, but through headphones it is very good, and I'm just using a pair of Ipod ear buds, tomorrow, I'm going out to buy a good pair of sennheiser headphones. I've layered the grand piano and the stereo piano as some suggested on the PX310 and PX110 and it sounds very full, the other voices are alright, I found the flute to be very good, I used to play the flute years ago, and it was kind of nostalgic to record a song to track one and then go back and play the flute voice with the track, it was even "breathy"
I think this is well worth the $700 I paid, you most certainly will get better voices and build quality if you spend 1000's on another keyboard, but I don't think you will get a better keyboard action for the money.
That's my opinion after having it one day, I might update this in a few more days, after I've gotten more accustomed to it, but my initial impression is WOW! what a great value.