I have the 50" Seiki. (Sears will be offering it for around $900.00 as a Black Friday Sale special.) I use it with 4K up-scaling Oppo and Sony Blu-Ray players. Decent picture (once you have it professional calibrated) for the money. However, here is the deal: when it is operated at UHD resolution with 24 fps source material, (or any source material under 24 fps that it will accept), the monitor only refreshes the image at 30 fps. As a result you get pull-up judder for the 24 fps (or less than 30 fps) material. Some people can see the judder, some people can't. But, it is there. Seiki is aware of this. So far, none of their software patches have fixed the problem. Also it seems that the 50" monitors are somewhat sensitive to the type/quality of the HDMI cables that are used, (premium Monoprice cables seems to work better than the cables supplied by Seiki), and it is somewhat sensitive to which HDMI input is being used (input no. 1 seems to work the most reliably).
Good value for the $$ for a first generation UHD panel. However, for mission critical work, I would look to a panel that can properly display a 24 fps signal (probably Samsung or Sony ... they have come down in price .... but are still more than the Seiki) and/or wait for panels that support HDMI 2.0.
