I was able to get a game in today with my Orks. I played against a GK player. We played a 1500 annihilation game. His list was roughly:
2 Squads of 10 Terminators; one squad had 2 psycannons, both squads had a banner.
Land Raider Redeemer
10 Nobz in a trukk with a painboy
30 boyz with a nob and 3 big shootas
20 boyz with a nob and 2 rokkit launchas
6 bikerz with a nob
5 deffkoptas, 5x tl rokkit launchas and 2x chain saws
All in all it ended up being a close game. By deffkoptas were gone by turn 2. He combat squaded 10 termies, and my bikerz wiped 5 + librarian in 2 rounds of combat. My warboss was killed along with 15 choppa boyz by an assault from the 10 strong termie squad, which was then wiped by a counterattack by the 30 boyz. His remaining 5 terminators counterassaulted what was left of the 30 boyz, and ended up 2 strong, and forcing that squad to run. At the end of the game I had the nob from the 20 boyz retreating, 4+nob from the 30 boyz retreating and the bikerz at half strength. He had 2 termies and a redeemer that had lost half of its weapon options. My nob squad was decimated in one round of shooting and 2 assault phases.
I learned a valuable lesson when playing against the Grey Knights: Assault at your own risk. The plethora of power weapons/force weapons brings woe to an army without any invulnerable saves. That being said, my orks faired pretty well. They smashed some grey knight faces, which was extremely satisfying. In the end, I made some tactical errors which probably cost me the win.