I thought 10 bit panels were technically superior, other things being equal ?
Don't 10 bit panels have a wider colour range and therefore less banding etc. ?
Or am I barking up entirely the wrong set of trees ?
You are correct, a 10 bit panel has finer gradiations between colours and greys, basically the number of different birghtness levels that each sub pixel can display is greater (2^8 = 256 shades per sub pixel giving a total of 2^24 = 16,777,216 colours for an 8 bit panel, compared to 2^10 = 1024 shades per sub pixel giving 2^30 = 1,073,741,824 colours for a 10 bit panel). Therefore, theoretically the colour is more detailed and accurate in a 10 bit panel.
The thing is though that this would either require better picture processing to interpolate these extra colours, or that the TV be fed with a source which takes advantage of the extra colours. A PC could certainly feed the TV with the appropriate colour depth, but I am not sure about the specifications for colour output of Blu-Ray for example.
Also, there is the argument that your eyes may not actually be able to distinguish such subtle variations in colour, since the 16.8 million colours of an 8 bit panel is already a lot of colours, would you honestly notice over a billion different colours? I don't know, chances are someone will say they can, although I suspect that it will not be a conscious noticeable difference, but rather just a generally slightly nicer texture to the image, but I could be wrong on that as I havn't (to my knowledge at least) seen a 10 bit panel next to an 8 bit one to compare.
I have no idea why the US gets 10 bit panels first, but I would hazard a guess that it doesn't matter too much considering that other factors such as picture processing and panel quality matter more than absolute number of theoretically available colours.