I find being on a bigger screen does not help. When I had a PC setup and plugge the Xbox into the monitor it looked nicer....
I also found when i had my previous tv which was a samsung Game mode on that was horrid the sharpness was far to high and contrast was over blown.. it just made the game look worse.
Bigger screens can exaggerate it even more yes have you tried tweaking the sharpness down and turning of any picture enhancements?

I thought so to. I was going to try and rid some of the motion blur, but left it in.