I'm using 500A for more than one years. It is the best TV so far except:
1) No iDTV (you have to use iDTV receiver)
2) Not quite smooth in moving subject
3) Hot, epecially in summer (but quite good in Winter).
I've compared 54" Z10H when I decided to buy 500A. If not compare side by side, I will go for Panasonic 54". But I compared panasonic 54" and 500A side by side, obviously Pioneer KO Panasonic.