Ran a couple of GH sides last night with three other guildies (we ran Trolls, Maze and Discord) on Elite R3.
Did not see one Champion but saw a lot of Reapers. In Discord we came across 4 Reapers that converged in the NE/SE arms. At the end fight there was a reaper on one of the pillars. Turned a normally tricky end fight into mayhem (we lacked an arcane nuker so it got sticky). The Reapers proximity debuffs/damage is pretty nasty. Not decided if it's overkill for them to debuff cleric heals the way they do (given self-heals are already debuffed).
Overall loving Reaper mode, it has certainly put the challenge and requirement for teamwork back into the game.