Anyone have any experience with the new 6.8 Remington SPC?? (Special Purpose Cartridge)

It was made for the AR-15 crowd. You can now buy the uppers for around $350. The advantage is that it shoots a larger bullet from a .223 rifle. (after changing upper. Should make a good deer cartridge. Some are getting 2700 fps out of 18 inch barrel with 115 grain bullet. very flat trajectory also.

I want to get this upper for my Bushmaster. Anyone out there have one??