I've also been following updates on this case since it began. Some thoughts:
As previously mentioned, it is kind of odd that his employer would file a missing person's report the day after the night out, knowing that he could very well be sleeping off a hangover. So, I wonder if his phone rang or not if they tried to reach him. Did the woman he was with at the T station try to reach him later that night to see if he got home? Did the phone ring or go straight to voicemail? Obviously it could have been turned off because it was out of battery power. Or, did someone turn it off or was it in the river?
I've been walking the path he is assumed to have taken. The spot the cadaver dogs picked up on is on the outbound side of the Clemente bridge. The stairs leading down to the trail are on the inbound side. If he had gone down there, why would he head to the other side? Did he drop his phone from the bridge and went down to try and find it?
Then again, there hasn't been any confirmed information he made it to the bridge in the first place. There are several cameras on Ft. Duquesne Blvd that could have spotted him, provided he made it that far.
Which takes me back to Katz Plaza. After that camera saw him, the next spot he had to have been seen on camera would have been at the entrance to the parking garage. There would have been no where else to go between the two cameras. The camera is right above the attendant both at the entrance/exit. He easily could have been hit by a speeding car leaving the garage, but that would have been on camera. So, after that camera, he would have made a decision to continue through Scott Place (I didn't see additional cameras until Ft. Duquesne Blvd) or go through the pass through to Barkers Place (where there are a few cameras on the way to Ft. Duquesne Blvd.). Maybe there are cameras in the pass through?
Here's where I have more questions. As mentioned before, there's really no reason to cut through Katz Plaza. Walking down 7th until Ft. Duquesne Blvd isn't much further and it would have been well lit with cars and probably people. It doesn't make any sense for him to go that way unless he was meeting someone. Let's not forget the Encore on 7th apartment tower that's right there...and connected to that parking garage. There is a door in the Scott/Barkers pass through. I haven't tried to open the door, but I'm assuming it leads to a stairwell that'll go to a door that leads to a skybridge into the apartment building. Was he meeting someone at that apartment building and/or in the garage?
Also, between Scott and Barker, and on Ft. Duquesne Blvd. is an abandoned building (an old PPG building?). Has that building been searched?
If there is no confirmed footage of DJ on Ft. Duquesne Blvd, then there are very few places he could have went and not been seen on camera.