How much calibrating do you plan to do on the 847u? I've never felt the need to pay $300, so I just do basic stuff like brightness, contrast, etc using the free AVS disc or whatever tools I find on the Pixar discs I have.
I'd be very interested in your results if you'd be kind enough to share.
I was very skeptical buying a TV with a yellow pixel, but I do like the rich colors on it and never plan to have it calibrated. I'm 90% sure the colors shouldn't look as rich and deep as they do and that the set would not calibrate well based on the professionally done Quattron reviews on the net.
Since sRGB and Rec.709 cover virtually all consumer content, what good is it having billions of extra colors if all you care about is reproducing the source accurately. It is impressive how Sharp crams that extra sub-pixel on smaller screens though.
Assuming 8 bit color (all that standard content is):
256^3 = 16,777,216 (normal TV)
256^4 = 4,294,967,296 (Sharp TV)
The engineer in me tells me I've been marketed to, but the cheap skate in me says I got a pretty good at cost deal on a pretty good TV so I should keep it since I like the color it produces

PS: Here's a great article I found written by the foremost expert in color reproduction:
http://www.maximumpc.com/article/fea...yths_shattered.