Yeah, they put up an invisible wall under the platform. I still dunno exactly where the cliff cheese spot is, but I found another spot that's even better than under the platform (I doubt I discovered a new spot... it's probably the cliff spot everyone else is talking about.). But when you first enter the boss area, if you stay up top, look high and to your left, there's a ledge that overlooks the whole battleground. If you jump up there, stay as far back as you can without falling down and squat. You can just sit there and shoot away at the arkon priest without him being able to hit you. Even the one sniper that can see you is too far away to shoot at you. And even if he does, that's the only guy you have to worry about. I did it twice and I didn't even have to move once.
Also ran the raid again and got Corrective Measure. I think I only need Praedyth's Timepiece, Hezen Vengeance and Atheon's Epilogue to collect all of the VoG weapons (or is Fatebringer another VoG weapon?) And still no armor (grrr!)
Normal VoG is cake for me now. I only died once and it was because a stupid supplicant blew up as I turned a corner as I was heading to the plate on the other side.