The SXRD is by far a better choicethan replacing the hitachi.
No SDE, 2ms response time, 13,300:1 contrast ratio, No rainbows, 1920x1080 resolution, excellent user menu, quality remote, good color, no burn in, no magnetic fields disrupt it, good viewing angles and excellent fill factor.
I am not surprised it looked better than your hitachi RP-LCD considering it beats it in almost everyway.
I own a Sony RPLCD and a Sony SXRD, both are 60'' and I can tell you from viewing both everyday that the SXRD is a far superior set. If you have the money than go for it. I cant recommend it enough.