I have a Darbee, my set is a LG LE8500 (full array, local dimming) I have also done a full calibration. My picture was already pretty awesome with my HTPC, I am using the best playback software, decoders and renderer available (to my knowledge) also I strictly use ripped Blurays (1080p/720p) with no compression.

The Darbee has made an improvement, the picture is noticeably sharper. I like it and it has become a permanent part of my home theater.
For every expert, there is an equal and opposite expert.