I had my Hitachi 57S500 done last year by Gregg and it is a night & day difference.
Colors are so much more realistic and he does a great job with focus. convergence, and even put duvetyne(black cloth) inside to cut down on the reflective glare of the painted black chip-board the cabinet is constructed with. I also had him take off the protective screen(no kids here) and it cut room reflections by 90%.
If you really into watching your TV, then have it done. You will be pleased.