Hi flakbait
There is a lot of info here:
http://64.177.53.248/ubb/Forum78/HTML/000512.htmland here:
http://64.177.53.248/ubb/Forum78/HTML/000619.htmlDr. Roberts is a wound ballistician and is involved in the development of the 6.8x43 mm round. In a nutshell it is meant to increase the lethality of shorter barrelled weapons which are hamstrung by the 5.56mm rounds velocity dependency. More lethal (better terminal ballistics) than 5.56, but lighter and less recoil than 7.62. As you can see on the first page, uppers have been developed for the M-4/M16 to make it a fairly easy switch. They were supposed to be able to use standard 5.56mm mags for the new round with a new follower, but someone from another board tested it out and the new rounds had problems fitting, thus I think one of the manufacturers involved will be offering new mag bodies.
If you want more links, I can point you to other boards, but I think the info on Tactical Forums is the best you can get publicly. They have a very high signal to noise ratio.
As for XM-8, here is another thread on TF which discusses it:
http://64.177.53.248/ubb/Forum66/HTML/000264.htmlIt gives you a good idea of the two sides for and against the XM-8. There's the side that says it doesn't do anything significantly better than the M-4, and the side that is very gee whiz about it.
mauser
P.S. About the cost of the XM-8, I think MiniD is right... something was fishy about the costs on that graphic, but I forgot where I read about it.