The new King Euphonium is 7.5 Lbs without the mouthpiece. The King K80 was 10.8lbs w/o the mouthpiece. (Per the Conn - Selmer Website.) There is a noticable difference between the two horns. The Deg was even harder to carry because the weight was heavier than the King, but the valve position was further forward making it even harder on the arms, shoulders and back. It was a beast.
I actually enjoyed Crowns Low Brass section this year. From the sound of the judges tape, they did also. Although, I have never played the Yamaha horns, I hear good things from those who are playing them.