On the phone they just said it would be a tournament. If there was a Gear 2 demo to play, I would have gone.
And I don't expect any bosses to be on Horde. Most of the bosses in Gears 1 were in planned areas, so fighting randomly generated ones wouldn't work. I expect there to be a flame thrower enemy or a shield enemy coming around every once in a while, but nothing like a berserker.